Heat loss calculations?


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Old 11-02-14, 03:52 PM
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Heat loss calculations?

Sorry if this is the wrong forum for this question but it seems like this could fit here or maybe in the HVAC section. I'm hoping someone can direct me to some sort of calculator to figure out what a "good" heat loss would be for a home given interior vs exterior temperatures and square footage. I'm trying to decide if there's something wrong with the insulation install I did this past summer. I have a ~1700 square foot "tri-level" home in the Pacific Northwest that was built in 1974. We bought it 2 years ago and last winter was our first year heating the home. It has a relatively new electric furnace and an old style masonry "heatilator" fireplace. The fireplace is rarely used and only for ambience and the damper is closed when not in use. Last year in the winter months our electric bill averaged over $300, one month it was $450. This summer we had a home energy audit and they recommended upgrading the insulation and doing some air sealing, but for the most part they were impressed with the "tightness" of the home's envelope given it's age. The windows and doors are all new, so we updated the crawlspace and attic insulation , R-30 in the crawl and R-49 in the attics. I also spent hours spray-foaming and caulking in an attempt to increase the air-sealing of the home. The crawlspace and attic hatches are all insulated and sealed and there is weatherstripping in the doors. Given all the time and money we spent on the insulation and air sealing I really hoped the home would be noticeably warmer this year with less furnace run time but it already seems like that's not the case. What is a "good" heat loss for a home this size and age? For example if it's 50 degrees outside and I run the furnace to heat the place till its 68 inside and then turn it off, how many degrees per hour should the inside temp drop? Right now if I run the furnace to 68 within less than an hour it's already down to 64, at night if we leave it off we wake up and it's ~58 and the outside temps aren't even down into the 40s yet.
 
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Old 11-02-14, 04:37 PM
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First, who is your serving utility, PSE or SCL? Do you know if you have a graduated rate plan?

I live in Bothell in a 1540 square foot single level home. Today I probably have my (gas) furnace run for about fifteen minutes on low fire and then twenty to twenty five minutes off to maintain 68 degrees inside. Overnight the inside temperature dropped from about 70 to 66 over about a six or seven hour period of time. I do not think my house is particularly well insulated and I know it is full of air leaks.

When you had your energy audit was it by the electric utility or by a "real" energy auditing company? Did they do a blower door test or any infrared camera observations? How about the surrounding area, is it fairly open or do you have a fair amount of shielding from the prevailing winds? IS your furnace "staged" along with a multi-stage thermostat or is it a single stage with stepped intervals between energizing the various elements?

Lots more.
 
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Old 11-02-14, 04:48 PM
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Why are you turning the heat off? Why don't you let the thermostat maintain your desired temperature?
 
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Old 11-02-14, 06:21 PM
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Thanks for the replies. We live in South King County on 2.5 acres, the property is on a creek nestled in a little bit of a valley but is fairly heavily wooded with good protection from the winds.

We have PSE for our utility services and I believe the plan is graduated, there's a summer and winter rate plan with $x amount for the first x # of kW's and then $y for anything over that. In the winter we went over into the higher rate for 2 or 3 months.

The energy audit was done by a contractor that was recommended by PSE, they installed the fan door and used a little smoke candle and IR camera. I caulked and spray foamed almost all the air leaks. The only places where we have poor insulation would be the exterior walls where the IR camera showed some sagging of the batts along the tops of the walls but the contractor didn't think there would be a cost/savings benefit in doing anything about that until next time we decide to re-side the house.

In regards to the furnace/t'stat that's an interesting question. The home inspector was a little shocked when he saw the unit we have, he said it's normally found in much larger houses or in commercial applications. The thought we had was that the previous owners planned on adding on to the house when they had it installed. It's a TempStar MF-20N hooked to a pretty basic Honeywell t'stat, it was made in '03 and installed in '04. I haven't had a specific HVAC guy come look at it, but an electrician that was here to do some other work was also shocked when he saw it, it's hooked to 2 60 amp breakers, he seemed to think we could get away with shutting one down and running it on "half power" but we've never tried that. I'm not sure if it's possible to wire it any differently than it is now but it's basically either on or off, super high/loud fan, runs for about 10 minutes to heat the place to 68, then its off for 5, on for 5, off for 5, on for 5, etc... It's annoying so that's why we try just to heat the place and leave it off for a while. Regardless of the furnace though, there's no reason this place should be cooling off as fast as it is.
 
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Old 11-02-14, 06:57 PM
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I need to take a nap, let me digest this for a bit and I'll post more later. The oversized furnace is definitely part of the problem.
 
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Old 11-02-14, 09:28 PM
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I can only type a short message right now as my arthritis is getting the better of me.

Can you post a few pictures of the furnace wiring panel with the cover removed? Also a clear picture of the nameplate. Pictures do need to be in focus and well lit. Although pictures under a certain size may be directly uploaded it is often better to upload to a photo hosting site and then post the public URL.

Many of the electric furnaces of that era had undersized (in my opinion) blowers and when coupled with smaller ductwork required high velocities to keep from overheating the elements. You might (if lucky) be able to slow down the blower somewhat and that would help with the noise.

The other factor that is contributing to your misery is that with the hugely oversized furnace you are quickly heating the air and the thermostat being satisfied shuts off the furnace. BUT, the house and contents are still cold and therefore the heat transfers from the air to the objects, cooling the air, setting off the thermostat and the whole process starts anew. If we can get that beast to slow down and release the heat to the air at a slower rate your comfort will soar.

Still more but I will await your response.
 
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Old 11-02-14, 11:05 PM
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Thank you Furd for all your help, if alcohol is ever your anti-inflammatory of choice let me know and I'll gladly drive to Bothell to buy you a "dose" to keep that arthritis in check. Here are the photos, let me know what you think, thanks again.















 
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Old 11-02-14, 11:09 PM
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Thank you for all your help Furd, the forum keeps rejecting my reply, I'm thinking maybe it doesn't like the "tinypic" URL links I added with the pics? Here's a link to the "album" I uploaded with the pics, let's see if that helps - http://************/a/397hi/1
 
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Old 11-03-14, 03:44 AM
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jr6424 -

All the theoretical calculations using "R-values" are just theory simplified or sugar coated. A "R-value" is related to time and rate as evidenced by the per "per hour" in the units of measure.

They never recognize the dynamics, so that makes them not very precise compared to the real world. The major factor missing is the thermal inertia or storage and the relationship to time. This factor also includes the buried materials and the soil. Obviously, a structure with thermal inertia is better suited to a small furnace that can run reasonably steady with no major hourly or daily peaks. The same applies to humidity and moisture from a comfort standpoint. - The end consumption of energy is much lower.

Dick
 
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Old 11-03-14, 07:03 AM
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Sorry, but links to Tiny pic are not allowed on here. There are several photo hosting sites you can upload to instead (let us know if you need recommendations) or you can upload your pics directly.

http://www.doityourself.com/forum/el...rt-images.html
 

Last edited by Shadeladie; 11-03-14 at 08:44 AM.
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Old 11-03-14, 12:27 PM
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My apologies, I'm going to try and upload them directly to the board and see if the resolution is still good enough to make out the details. Is there a known problem with the tiny pic site? Is it just an advertising thing or is it known to host viruses or something? I ask out of ignorance so I don't make the same mistake somewhere else, and yes I'd love some recommendations for a better photo hosting site, thanks!
 
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Old 11-03-14, 12:52 PM
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Old 11-03-14, 01:06 PM
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Old 11-03-14, 01:36 PM
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I'm following as well, been digging out of our latest east coast snow.

I agree that the oversized furnace is contributing to some of the issues, but I agree with you jr that the temp drop is still an indication of heat being lost somewhere.

While Furd deals with the furnace, what did they give you as a report on your energy audit.

Did they list the leakage number, CFM50 = ?
Did they list the insulation levels they used with their calculations?
Did their heat loss match (reasonably well) with your actual use?
The insulation added to the crawlspace, was that added to the floor above?
Are there any supply or return ducts in the cold area of the crawlspace?
Did you get any Infrared pictures?

If this was a real energy audit you should have been given more than just an estimate of what they thought was needed for work.

More later.
Bud
 
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Old 11-03-14, 02:33 PM
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Thanks for the help Bud, the results from the audit were after the crawlspace, but before the attic work and air sealing:

Actual Blower door results - 2567 CFM50, "Target" should be 1464.

Actual Air Changes per Hour .62, "Target" .35, they list that as "moderate" leakage but within reason for a house of this era.

As far as R value calculations from the paperwork they listed "estimates" as to what they felt the current R values were, if that's what you mean. They list duct work as R9-11, Attic (before) as R15-30, Walls as R7-13, and crawlspace as R30.

Not sure what you mean about heat loss matching with my actual use, but honestly I haven't seen much of an improvement in before/after if that's what you mean.

Yes, the insulation was added in between the floor joists, common fiberglass batts secured with crisscrossed twine. I asked why they used that vs the metal prongs and they said they have had far better results, when the attic guy came he was impressed with the crawlspace work. The vapor barrier was replaced as well.

There are supply, but no return, air ducts in the cold portion of the crawlspace but they are all wrapped in new insulation.

They used an IR camera to show me where the cold spots and leaks were, but they didn't leave images behind when they left. They showed sagging insulation on the walls and cold spots around a lot of the ceiling and baseboard junctions, I caulked everything from the inside of the rooms and when the attic was done I spray foamed everything from up top before they blew in the new insulation.
 
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Old 11-03-14, 03:11 PM
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Here's some photo hosting sites that are often used on here:

Photobucket: Photo and image hosting, free photo galleries, photo editing
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Shutterfly: Photo Books, Holiday Cards, Photo Cards, Birth Announcements, Photo Printing | Shutterfly
Imageshack: https://www.imageshack.us/login

There's more, but those are pretty popular.
 
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Old 11-03-14, 04:10 PM
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@"Not sure what you mean about heat loss matching with my actual use," From their calculations they can estimate your actual use. If that number is close to what you are actually using it adds some confidence level to all of the guesses they had to make getting there.

A CFM50 of 2560 is on the leaky side and they should be offering a return visit to verify your air sealing. The 0.62 ACH is arrived at by dividing the 2560 by 18 (an LBL conversion number), multiplying that by 60 for hours and divide that by the volume of your conditioned living space. Ok so far. But the 0.35 target is an old number used to avoid needing extra fresh air. Now, it would be rare that you could get below 0.35, but lower is better. You could deal with the fresh air in other ways. But, without an after blower door test you have no way of knowing how much more is needed. I'll add a link on air sealing for your review in case you can identify something you/they overlooked. It is the big leaks that are far more important than all of the little ones, but don't leave any that are easy to get to unsealed.

One last comment. You are looking for something substantial and you have already discovered that the added work you completed was probably small potatoes. The oversized furnace is being addressed. Air leakage is still way too much (my guess) and is part of your heating bill. Duct leakage and pressure balancing can be a factor as high pressure pushes expensive air out to be replaced by cold air coming in.
Bud

http://www.efficiencyvermont.com/ste...ide_062507.pdf
 
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Old 11-07-14, 02:11 AM
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Jr, I haven't forgotten you. Your problems ARE significant and they deserve more than a one or two line answer. While I develop that response I want yo uto try turning off the 50 ampere circuit breaker at the furnace. This should still allow the control circuits to be engaged but not allow the higher stages of heating elements to engage. The air will exit the supply registers at a much lower temperature and the furnace will run for a longer period of time to achieve the thermostat set point. Try not to use a deep set back of temperature when sleeping or away and let it run for several days in this manner and see if the very rapid drop in temperature during the off cycles is lessened.

Post back with the results.
 
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Old 11-08-14, 12:13 PM
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Bud - that's a great guide book, thank you for that. I'm going to get the audit people back and see if we can get new numbers. I don't think there is anything much in the way of "substantial" leaks that I've overlooked although the results would seem to indicate otherwise.

Furd - Killing the 50 amp breaker at the furnace substantially lowered the air temps at the outlet, I don't have an accurate thermometer but suffice to say it was a noticeable difference, the air was "hot" with it on, and "lukewarm" with it off. The run time results though were a little puzzling, with the breaker ON, t'stat set to 68 and outside temps hovering between 48-52 run time over an hour averaged 2:14 on and 7:25 off with 6 on/off cycles, same conditions with the 50a breaker OFF resulted in 8 on/off cycles averaging 2:43 on and 4:37 off. Let me know what you think, thanks again!
 
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Old 11-08-14, 06:55 PM
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At this point I am looking more for comfort than for cycle times. Let it run for a few days with the 50 ampere CB off and then let me know IF the house seems more comfortable, less of a "freeze or fry' syndrome.

I really think that a substantial part of the problem is that the vastly oversized furnace is only heating the air and the contents along with the interior structure is not getting a chance to warm up. This could be especially true if you have a deep temperature setback during sleeping or away hours so IF you are using setback, disable it for this test.

On the other hand, your results from the "energy audit" show that you have a "leaky" house and until you address that you will continue to have a problem. You may also have a problem with the return air ducts and grilles as well as with the thermostat placement.

In my own house the thermostat was originally placed on an inside hall wall about one lineal foot away from the single return air grille located in the ceiling. In thins location the main living area was always cold and the bedrooms would overheat. Moving the thermostat about five lineal feet around the corner to more sense the living area temperature made all the difference in the world in comfort with the living areas warm and the bedrooms not overheating.
 
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Old 11-08-14, 11:20 PM
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jr, the run results you reported sound correct from my perspective, although I don't know what was disabled with that breaker off. But delivering lower temp air will take a bit longer to satisfy the stat, yet will not have filled the delivery pipeline with extra high temp air, thus the new cycle starts earlier. Again, from my perspective, it is the heat loss that ultimately determines the off cycle. Thermal mass can be a part of the cycle time, but, like charging a capacitor, it will find an average after a few cycles.

I like to break down my audits into 5 basic areas, ceiling, walls, windows, floor and foundation (all together) and air leakage. Each of those surface area categories can have several components like different windows or walls with different r-values, but it provides a weather vane to point you in the direction of the primary heat loss. Depending upon how they run their calculations they may not be able to do this, but obtaining the data they keyed in for those area would allow us to do it.

Tri-level homes, if I'm viewing yours correctly, can result in floor cavities meeting wall cavities somewhere in between the top and bottom of some walls resulting in hidden connections or air paths. A second blower door test with the Infrared camera (have them let it run for 10 or 15 minutes at a lower pressure) with a good temperature between inside and out, should locate any hidden paths. As the fan runs longer you will see the cold areas grow in the direction of the air flow, although that direction is being forced by the fan and may not be the same under natural pressures or wind.

I noticed your audit was done during the summer. Summer temperatures are far less revealing when viewed with an IR camera. You can do an IR inspection in the not so cold seasons, but it takes some extra steps to establish a working delta t and the results need careful review. I just wait for cold weather, much easier and better results.

Bud
 
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Old 11-10-14, 09:24 PM
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Furnace "Closet" with first return, in daylight basement.


Kitchen with Thermostat, main floor.


Staircase (opposite side of wall w/ t'stat) from main floor to upstairs with the 2nd and 3rd return.
 
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Old 11-10-14, 09:35 PM
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Thanks again to everyone for all the help, I'm 36 hours in to the "test" with the 50 amp breaker off and leaving the thermostat set to 70 with no setbacks. There is definitely a huge improvement in the comfort level, no more freeze/fry cycles. Run times vary depending on time of day but when the sun is out we're down to maybe 3 cycles per hour, at night back up to 6 or 7. The usual program I ran had the temp set to 68 an hour before we woke, 58 while we were gone to work, back up to 68 an hour before we came home, and then down to 62 while we slept. I've attached a few pics below with the t'stat location compared to the returns. I'm not super happy about it being in the kitchen and so close to the fridge and oven but we don't cook that much that I think it makes a difference. The returns are on the opposite wall so I don't think they influence it too much. The supply vents are scattered throughout in the floors but none anywhere near the stat. I think letting it run for as long as it has now has definitely allowed the floors and contents to warm up and help buffer that constant chill we had, but I'm still concerned that the furnace seems to be running too much and "short-cycling" at night. I've thought about upgrading the t'stat to one of the fancy new automatic learning Honeywell's but with only the 2 wires I don't think this furnace would really take full advantage of its features. I'm also definitely going to get the audit people back to see how the numbers play out now that's its winter and after the new insulation and air-sealing work.
 
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Old 11-11-14, 01:33 AM
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Bud, leaving that 50 ampere circuit breaker off essentially cut the size of the furnace in half.

Without actually being able to measure the sizes of the return air duct I am going out on a limb but I think you are starving that furnace for air. Would have to connect a manometer to be certain. AND, if the return ducts are minimally sized there is a good bet the supply ducts are also minimally sized.

Moving the thermostat might help tremendously as might using a modern thermostat that controls the cycles per hour. How difficult would it be to string a new thermostat cable?

Also, now that you know the furnace is way, way too large it may be possible to slow down that huge blower as well. I need to see pictures of the blower motor wires and connections as well as the thermostat wires and connection on the furnace.
 
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Old 11-13-14, 01:31 PM
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Sorry for the delay, I fell victim to the wind storms down here and have been without power for a few days. Question, if we slow down the blower would that then negate the need to increase the size of the return ducts? If we can't slow down the blower would that necessitate somehow enlarging the ducts? Do both need to be accomplished? Running a new cable to the existing thermostat location would be easy. Moving it wouldn't be too hard either, but the question would be where to move it to? That dividing wall between the kitchen and staircase is essentially the only interior wall on the entire first floor, the rest is an "open floor plan" layout so any other wall would be an exterior wall which all have either windows or doors and are very close to the supply ducts. Here are the pics, not sure which wiring diagram applied to I took pics of them all. Let me know if you need more detail. Thanks again!























 
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Old 11-14-14, 09:34 AM
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I've been pondering this for several hours and I am at a point where I have more questions than answers. The documentation for this unit is, in my opinion, very poor. The wiring diagrams do not use standard symbols so I have had to make some educated guesses. The two wires that come down from the control board to a pair of wire nuts that are then connected to wires going to the blower are a bit confusing as is the extreme amount of extra wire from the blower motor capacitor and the speed control wires that are simply bundled together.

Something else bothers me and that is that generally there are two speeds used for such a unit's fan. A lower speed for heating and a higher speed for cooling. (I know you don't have cooling but the thing should be set up for it.) Unfortunately, I do not see a speed selecting relay in this unit.

What I would like is to install a two-stage thermostat and use just one bank of heaters under normal conditions with the second bank available for pick up from a deep setback or in case it gets so cold that the primary heater bank cannot keep up. In the perfect world that would allow the blower to run at a lower speed most of the time and only go to the higher (noisier) speed when the second stage of heat is called.

So, your assignment for today is to unbundle the wires from the blower motor and determine which wire corresponds to what speed. I know there is a white wire that is wire-nutted to a yellow from the control board as well as a black that is wire-nutted to a black from the control board. There should be at least a red and blue wire with no connection and there may be a third wire with no connection. Hopefully there is a nameplate or stamping on the motor itself that designates the speed for the different colors and if so, please post that information. Otherwise it will be a trial and error procedure. (If no designation of speed/wire color can be found I will instruct you on how to proceed later.)

I also want you to remove the jumper wire between W1 and W2 on the thermostat connection terminal strip and turn the 50 ampere circuit breaker back on. Without the jumper the furnace will still only operate on the first stage of heating.

One last thing. After doing the above teat the furnace making note of the noise of the blower. Then add a jumper wire between the R terminal on the control board and the G terminal. This will energize the blower manually. Note if the noise is the same, more or less. Then remove the jumper.

Post back with the results.
 
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Old 11-15-14, 09:46 PM
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Hope you won't get sick of hearing me say thanks, but you're definitely going above and beyond with this, I seriously owe you one when we get this all wrapped up.

OK so here's what I've found out so far - There are 2 bundles of wires leaving the fan:

The first is 4 wires - 2 orange and 2 purple that just loop back into each other, orange to orange and purple to purple.

The second bundle has 7 wires, 2 brown that go to what I assume is the blower's capacitor (silver battery pack looking thing attached to the blower motor housing,) 1 blue that is wire nutted to the black that goes to a PC board connector labeled "Fan Speed," 1 white that is wire nutted to the yellow wire that goes to a PC board connector labeled "Fan Com," then there are 3 wires that are just terminated in a loop with electrical tape, 1 red, 1 yellow, and 1 black.

None of the wires are labeled, no placard noted on the blower motor itself. The only label I found on the motor was one that said "Warning, Disconnect Power Before Reversing Rotation."

I also noted that in the top right corner of the PC board there is a "blank" area labeled "2 Speed Relay." I've attached a pic below.

I removed the W1-W2 jumper and reenergized the 50 amp breaker, same lower temp as we noted before, no other differences noted.

I added the R-G jumper and there was no perceived difference in fan speed/noise with or without, BUT the fan never shut off. It continued to run and blow cold air between heating cycles. I checked the t'stat to make sure the fan switch was set to "Auto" and not "On," I tried both positions with no change, just constant fan running so I went ahead and removed it.

So as of now we have both breakers on and the W1-W2 jumper removed. I await your further instructions. Thanks again!

 
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Old 11-15-14, 11:36 PM
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I never get sick of people thanking me for my help and you are quite welcome to it. What I, and the other responders here dislike is after we have gone through a discourse of making suggestions and asking questions and the original poster never returns. You are not like that so I continue to offer suggestions.

Easy ones first.

The jumper between the R and G terminals was just a test to see if you had a high speed fan relay, which you don't. Your existing two-conductor thermostat cable doesn't allow for the fan switch on the thermostat to do anything but amuse you when turning it from one position to the other. My personal opinion is that all thermostat cables should be a minimum of seven conductors and nine conductors are not too many. That you only have a two-conductor cable is just another indication that the builder or his HVAC subcontractor was a cheapskate.

Did you use a mirror and flashlight to check all around the blower motor for anything concerning the speed? It isn't really important but it would make the next steps a little easier.

Ignore the bundled orange and purple leads as well as the two brown leads that go to the capacitor. The white from the motor that connects to the yellow with the wire nut can also be ignored. Disconnect the other wire nutted connection and insulate the blue from the motor with either tape or another wire nut. Strip and connect the yellow motor lead to the black from the circuit board and then power up and notice if the blower speed is more or less than it was with the blue lead. Try this with the red motor lead and the black motor lead as well to determine the speeds associated with the different colors. Be sure to insulate any unused leads before re-powering.

Now here I am guessing, I suspect that the black motor lead will be the highest speed, the blue a bit slower, the yellow slower still and the red the slowest. Correct me if I am wrong. Whichever lead is slightly slower than the blue leave connected and then run the furnace for at least ten minutes, noting the relative temperature of the discharged air. It should be warmer than when the blue lead was used but not as hot as when both heating elements were used. If this is all true then run a few days and see how the comfort level is, both temperature and noise level.

How do you feel about installing a fan speed relay? I wouldn't mount it on the circuit board but as a stand-alone. This would give you the ability to use the second stage of heat for fast warm-up if necessary.

BTW, how cold did it get inside and how fast did the furnace recover when you were out of power last week?
 
  #29  
Old 11-15-14, 11:57 PM
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Just going through the entire thread again and I see I didn't fully explain this:

Furd - Killing the 50 amp breaker at the furnace substantially lowered the air temps at the outlet, I don't have an accurate thermometer but suffice to say it was a noticeable difference, the air was "hot" with it on, and "lukewarm" with it off. The run time results though were a little puzzling, with the breaker ON, t'stat set to 68 and outside temps hovering between 48-52 run time over an hour averaged 2:14 on and 7:25 off with 6 on/off cycles, same conditions with the 50a breaker OFF resulted in 8 on/off cycles averaging 2:43 on and 4:37 off. Let me know what you think, thanks again!
Very rough calculation shows approximately a 19% energy saving when the 50 ampere circuit breaker is off. Along with the improved comfort this is encouraging.
 
  #30  
Old 11-17-14, 03:01 PM
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I've found this thread after having similar issues to the opening post. I live in Minneapolis (1950s) single story home. Hip roof, finished basement. Original fiberglass insulation barely covered the joists in the attic. We installed soffit vents, sealed all the gaps we could get to without disturbing a massive amount of insulation, and then blew in enough cellulose to get to 20" (fiberglass and cellulose combined).

This was a few weeks back that we finished the attic. We feel now though that the furnace is running just as often if not more than before when we had about an R-20 in the attic. We have the thermostat set at 68 when we're home, dropping to 60 overnight and when we're gone.

Reading this thread I found a lot of similarities to our home. The furnace blows really loud and then comes on 7+ times an hour. I wonder if we aren't also experiencing some of the same issues as JR.

We need to have an energy audit performed. All we've done so far is rent the IR camera to take photos (all prior to the attic insulation). The other thing I notice is that the walls are very cold as there are also cold spots on the main floor. The finished basement is very warm. I think the insulated walls down there are 8-10 inches and it's never cold.

Where do I start to see if I can improve my home? I feel like I've spent a lot of money and gotten very little in terms of keeping my house warm...
 
  #31  
Old 11-18-14, 11:23 AM
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Is anyone able to offer some suggestions? Is it possible to run my furnace on these settings if I were to take images as JR has? Trying to get the audit setup for this weekend.
 
  #32  
Old 11-18-14, 01:58 PM
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Sorry for the delay, I electrocuted myself and am just getting out of the hospital now... Sorry bad joke, my work schedule has been a little crazy so I just now got around to trying this out. OK here are the results, as you suspected I believe the Black would correspond to "Very High," Blue "High," Yellow "Medium," and Red "Low." However I will say that the difference between Black, Blue, and Yellow was only mildly noticeable while Red was definitely significantly slower and quieter. I've got Yellow hooked up now and will run it for a few days and see how it feels and sounds, the boss's ears are more sensitive than mine so hopefully she can chime in when she gets home. All 3 of the higher fan speeds cause "oil canning" popping sounds in the ducts when they turn on and off while the Red definitely does not, unfortunately I don't think the Red gets much airflow to the duct in the upstairs back bedroom. Is there a less subjective way to test these speeds/temps? Should I invest in a manometer (not sure how to use it in this application though) or maybe an instant thermometer to test the outlet air temps?

I did use a mirror (actually my cell phone camera) to check all the accessible sides and nooks and crannies looking for labels or placards, the only thing I found was a half peeled off UPC type sticker on the inside of the squirrel cage, it doesn't look like it has any relevant info on it, but I'll post a picture anyway in case it helps you.

I would love to install a fan speed relay if you think that would help, and/or a newer 2 stage thermostat as you suggested earlier, especially if you think it's something you could walk me through. I'd love to run more wires up to the 'stat if that would help also, but is this furnace capable of taking advantage of them?

As far as the temps during last weeks power outage, while the sun was out the house held its temp pretty well, it dropped down to 62 pretty quickly during the day but then held that and slowly worked its way down to 58 by night. Then we woke up to 48 degrees in the house the next morning though. It warmed up to 52 once the sun was up for a while. After the power came back the furnace ran almost constantly for close to 2 1/2 hours to get the temps back to 68, taking short breaks along the way to avoid overheating I suppose.

Thanks so much again, I anxiously await your instructions!
 

Last edited by jr6424; 11-18-14 at 02:12 PM. Reason: added link to pic
  #33  
Old 11-19-14, 11:16 PM
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User ISOWTC Insulation Software for the Heat Loss Calculation.


Thanks,

Heat Loss Calculation
 
  #34  
Old 11-21-14, 06:16 PM
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Quick update, 3 days in with the new setup and we're very happy with the results thus far. I think the noise difference is negligible, but the wife is happy and says it's definitely quieter and the "oil canning" is almost completely gone. Comfort levels have soared through the roof and cycle times are way down. I think that has more to do with cutting down on the setbacks as you suggested, but either way results are very encouraging. We're set at 68-69 during the day and 66 at night and when we're away. Morning cycle times are similar to the previous results but once the temp has leveled off for an hour or two we're down to maybe 6 cycles an hour, 2-3 minutes on and 8-12 minutes off. Thanks again for all the help! Curious to hear what you think of where we're at and what we can do about the fan speed relay and/or thermostat upgrade.
 
  #35  
Old 11-25-14, 01:40 AM
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Sorry for the delay, I electrocuted myself and am just getting out of the hospital now... Sorry bad joke...
I really was in the hospital, Evergeen in Kirkland if you want to check it out.

Glad to hear things are looking up as far as the furnace is concerned.
All 3 of the higher fan speeds cause "oil canning" popping sounds in the ducts when they turn on and off while the Red definitely does not...
And yet another indication of a lousy install. Oilcanning is a result of using ducts too small, incorrect blower speed, restrictive filter(s) or return air grilles or, if rectangular ducts are installed, the fabricator not "cross-braking" (putting an X crease across the flat sides) the ducts.

Definitely I could "walk you through" installing a new thermostat and cable and yes, I think the improvement would be worthwhile. Adding the two-speed fan relay is also a fairly easy task.

What I need now is a temperature differential reading across the heating elements and an outlet temperature. You can approximate the differential by taking a return air temperature measurement at the RA grille closest to the furnace and then a discharge temperature at the register closest to the furnace. May need to eventually get a more accurate reading from the furnace itself. Also, a final discharge temperature which again, can be approximated from the supply register closest to the furnace. IF these temperatures are low enough then you may be able to run on the lowest blower speed.

Something else to consider, Listen closely at the return air grilles and see if that is the primary source of noise. Touch the grille and see if the noise changes in pitch. If yes to either, remove the grille and see what happens to the noise. You MAY just have overly restrictive RA grilles.
 
  #36  
Old 11-27-14, 02:05 PM
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I really was in the hospital, Evergeen in Kirkland if you want to check it out.
Whoa, really sorry to hear that. Hope you are feeling much better by now and are well along the path to recovery. If there's anything I can do to help please don't hesitate to ask, I'm involved in the healthcare industry in a roundabout way so if you need a referral or recommendation or anything just ask. I can send you my email and phone contact info privately if you need them.

Also, Happy Thanksgiving! After the unseasonable cold snap we had last week, now we're into an unseasonable warm spell, not that I'm complaining, but the furnace has hardly been running and I haven't been able to get all the measurements you're looking for till now. I went down to Harbor Freight (I know...) and bought a few different kinds of temp probes, I'm looking for one of the old fashioned ones like my father used to keep in his pocket protector when he did HVAC work back at JFK ages ago, but now everything is "instant" and "digital" and I'm not sure if they are actually measuring what I want them to. I'm not sure if I'm measuring these properly, but the best I've been able to come up with is to try and capture the temp of the air passing the closest return grill and the closest supply register. They seem to vary wildly but average out to 66.8F on the return and 92F on the supply side, making the differential ~25.2F. The highest I saw on the closest supply was 94.8F.

As far as the noise there doesn't seem to be any change in pitch near the return grilles, but the oil-canning is definitely coming from the rectangular duct on the last leg (maybe the plenum?) of the return side. I'll get a few pics up, but the return ductwork is all rectangular, with the stamped "X" except for the last piece closest to the furnace, I can recreate the sound just my touching it with my hand, the furnace housing itself is also a bit "soft" and can be made to make the noise too, but I can watch the return duct "suck in" when the cycle starts and then "bow out" when it stops.
 
  #37  
Old 11-27-14, 03:05 PM
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The actual rectangular return duct size is 25"x10", here are some pics of the grille's and actual inside sizes of the 2 upstairs return ducts, the 3rd and final duct is right next to the furnace itself.

Return 1 Outside (Grille) 9.5"x16"
Return 1 Inside (Duct) 9"x13"

Return 2 Outside (Grille) 26"x10"
Return 2 Inside (Duct) 16"x7.5"

Return 3 Outside (Grille) 26"x10"
Return 3 Inside (Duct) 21.5"x6"x3.5"

Duct 2 Grille Width


Duct 2 Grille Height


Duct 3 Grille Width


Duct 3 Grille Height


Inside Duct 2


Duct 2 Inside Depth


Duct 2 Inside Width


Inside Duct 3


Inside Duct 3 Width


Inside Duct 3 Height


Inside Duct 3 Depth
 
  #38  
Old 11-28-14, 01:28 PM
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One more quick update, I removed the register from the closest supply duct and got the temp probe in there for some more accurate measurements. The highest reading was one quick spike to 101.2, but the average was still in the low to mid 90's, higher toward the end, but right before the end of the cycle it cools off dramatically. As if the elements shut down but the fan runs an additional 15 seconds or so. Not sure if that's normal or makes a difference but I thought I'd add that info in.
 
  #39  
Old 12-01-14, 10:29 AM
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Little more info, seems we've had a relapse now that the temps have dropped again (daytime high's hovering around freezing, overnight lows into the low 20's) we're back to almost 10 cycles per hour, 3.5 mins on/3 off ad nauseam just to hold 67 in here with no setbacks. Comfort is still good with out the freeze/fry cycles since we've eliminated the setbacks, but the short/loud/frequent cycles are getting on my nerves. The longer the furnace runs the hotter the discharge air is, I saw it as high as 103.4 but it's averaging around 101. Now that the temps have dropped is it time to reenergize the second bank of elements?
 
  #40  
Old 12-01-14, 11:15 AM
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Sorry for not responding earlier, this medical problem is tiring.

As long as the furnace is cycling there is no reason to energize the second set of elements. My furnace has been cycling on the first stage (about 35,000 BTU/hr. output) and maintaining the inside temperature just fine.

However, you DO have major duct issues with the return air and I can only guess that is also true of the supply ducts. Since the supply temperatures are still running decently low I would suggest going down one more step with the blower speed and see how the discharge temperature is running on a prolonged call for heat. Ideally, if you could drill a small hole (about 1/8 inch) in the supply duct about a foot (more or less) after the furnace proper this would be the best place to take the discharge temperature. Same with the return only before the furnace proper.

Look on the label for the furnace and see if there is any wording regarding the temperature differential or a maximum supply temperature. Going just by normal practices your differential and maximum supply temperatures are not too high and that would indicate that a lower blower speed might be acceptable.

Can you leave the return air grilles off for a period of time? The answer is no if you have a cat and maybe no if you have a small child. I ask because you might get a bit more airflow into the RA ducts without the grilles in place. Also, check that air filter under the blower housing and make sure it is clean.

What city do you live close to? It might be getting time for a road trip.
 
 

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