Hi Everyone,

I’m in the process of buying a new oil boiler and I am grappling with the problem of whose heat-loss analysis to believe: mine (my extensive experience in this area extends back about three weeks) or the two heating contractors that have been to my house.
I live in an 1860 farm house in Rhode Island. The house is 4400 square feet, three stories (although we don’t typically heat most of the 3rd floor). The home was, decades ago, a duplex (but is no longer) and has two 35-year old boilers. One of these has died, so I’m working on re-doing my entire heating setup. The house has storm windows and storm doors all around, insulation blown into the walls (I believe all of the walls), insulation in the attic and basement.
After reading some helpful posts here I did two things: I downloaded the SlantFin Hydronic Explorer program and used it to make several heat-loss estimates based on various assumptions (I don’t know everything about my house). I also later purchased the HVAC-Calc program and (re-measuring everything) use it to make more heat-loss calculations. Using an outdoor design temp of 9 degrees (that’s what seems to be recommended for my area) and a fairly generous indoor of 70 (we usually heat to 68), I get a heat loss of somewhere between 100k and 120k BTUs – even assuming that we heat our 3rd floor (I guess we want the ability to do that in case grandma suddenly decides to move in with us).
The two heating contractors who have visited didn’t want to know anything about my window or door sizes, insulation, storm windows, etc. Each simply took the square footage of my house and used this as a basis for their heat-loss estimate. They each used 0 degrees as an outdoor design temp. One of the contractors (who, honestly, seemed quite knowledgeable) told me he used the formula of square footage times 32 to calculate heat loss. His estimate for my heat loss is therefore 141k BTU. The other guy (who didn’t divulge his secret formula) told me that I needed 165k – maybe more based on his measurement of how much baseboard I have.
What should I do? I think that both of my contractors believe I’m a little nutty for telling them (politely) that, based on my non-existent experience, I disagree with their heat loss estimates. The 165k guy told me I might have to sign a waiver if I ask him to install a boiler smaller than he recommends. How do you get someone to do a real heat loss analysis for your home?
Thanks for the help….

Charlie and Razz

 

I would not do business with someone that was so irresponsible to say what you need without seeing the house. the request for a waiver is an obvious out or may just a complimentary bid pushing you toward the other. - I have no information on your home, so I cannot comment on the size. Going to a local oil supplier may not give you any better references, but it is definitely worth a chance.

I would look for a more responsible contractor, but that can be a little difficult in your part of the world where too many are tooo close.

Look for another contractor that has a different nationality that the ownership than the two previous quotes. - I lived in eastern CT and dealt with many contractors in another industry, where cash in an envelope was an extra to be given to the delivery driver depending on the location (state, going west mainly). An envelop with a signed delivery receipt was in the envelope. The auditors and the bank had a hard time when they discovered the cash payments when the drivers were paid by the load and by the hour.

It is a great place/area to live and eat though!!!

 

I just have to jump in here, because I am a contractor that bids heating jobs.

First off, let me bring to your attention that most people get more than one bid.
Secondly, the price of gas is over $4.00 per gallon, and with the economy the way it is, we need to go even further to find work.
And let's not forget, everyone wants that estimate/bid for free.

I usually do my free heat losses just like the first guy did. Square footage multiplied by a general heat loss factor. I have received that factor from my supply house and has kept many people happy for many years.
I realize in todays fuel market, you don't want to grossly oversize a heating appliance, but you also do not want to undersize it either.

I don't even write my bid until I get some kind of confirmation unless specifically requested differently.
And usually when I write something on paper, it has become a contract, not a bid.

Granted, there are some companies that are getting pretty wealthy by selling and installing heating systems at a high mark up, and if you choose to use them, so be it. There mark up is so high, they can afford to spend hours doing a proper heat loss at your home. And if someone wants to pay my hourly cost, I will certainly do a complete bid with all the numbers as required.

I, on the other hand, are like the other 80% of the installers out there that are struggling to survive with 1-5 man shops.
It makes it difficult to spend that much time measuring all the doors and windows etc., when we are possibly not even going to get the job.
I have even started charging for bids, and refunding the estimate charge from the contract price if I get the job.

There is also one more thing to consider.
When you do a complete heat loss on a home measuring everything like the programs advise, you will be buying a system that is too close to ideal conditions. What happens when we get those occasional freezing spells and the boiler/furnace you chose is not big enough to handle the load. Yes, maybe it is only for a few days a year, but you have just become a dissatisfied customer and you tell everyone you know that the system I put in couldn't keep up with the cold snap and now I have a bad name in the industry.

Also what happens when you decide to finish a room or two in the basement and the boiler is already at its max. Now you need to upsize the 3yr old boiler you just put in for thousands more.

I am not saying who is right or wrong here, just that there is a lot more to consider than just a heat loss number.

Thank you for your time, Mark

 

Are you sure about the outdoor design temp? We have seen colder days here n Maryland.

You have 3 calculations. Why not just use the middle value of 140k? Or redo you calculation with a design temp of 0 and see how much closer it gets to the other 2.

 

Interesting set of questions and responses.

Some thoughts and some questions.

1) what kind of heat emitters do you have? Radiators? Baseboard?

2) an 1860s farmhouse is something of a special case where heat loss is concerned. Speaking from experience having participated in a major refit of an 1830s farmhouse a few years ago.... Chances are you did fine with the Slantfin-ware given how conservative it is, and the assumptions you made about the efficacy of the storm windows, insulation, etc. For most post-1960s construction, the standard "Manual J" heat loss calculation that Slantfin-ware does seems to result in about a 30% overestimate of the heat loss. But since you're dealing with a structure about a century older, things are probably different.

3) can you make it through next winter without upgrading the heating system? Reason I ask is that a "real" heat loss is based on physical testing, such as thermal imaging (which works way better in the winter when the surroundings are cold and you can see the leaks and missing insulation areas much better), and a blower-door test (which measures infiltration/exfiltration -- not as sensitive to outdoor temp, but often firms that do thermal IR also do blower door tests). We did both for the 1830s farmhouse. It helped A LOT and was definitely worth the money. We also had some questions about the thoroughness of the blown-in insulation. So the GC on the job called the thermal imaging guy back after the blow-in. Guess what? We found all kinds of pockets missing insulation. Some entire stud bays were empty. Problem was the blow-in guys doing the job were used to standard 16" O.C. framing, and hadn't done many older, non-standard buildings. We used the second round of thermal IR to get the insulation guys back and finish things up right.

3) I agree with plumbingods about charging for estimates that include a thorough heat loss. These guys gotta make their money, and given the average success rate, it's not worth their time to do much more than what they're used to. That said, there are SOME guys who have seen enough houses over the years, of similar construction, that they can get in the ballpark for sizing just by a walk-through. But anyone who wants you to sign a waiver should be out of the running.

4) plumbingods also makes a good point about sizing based on current requirements and not having enough overhead if you decide to add on, e.g., in your case heat the upper floor. In response, I say first try to look into the future as to what's most likely. Second, if you go with a gas-fired modulating/condensing boiler (and if gas is an option, you absolutely should), the modulation range of the boiler will forgive some of the oversizing.

5) An outdoor design temp of 0-9F is fine. Here in southern MA that temp range is common for design. I disagree with plumbingods that when the inevitable two-week super cold snap occurs that you will actually get cold. By definition, the design temp only occurs something like 0.4% of the year. Some years more, some less. If for some reason the heating system can't keep up, put on a sweater, grab an extra blanket, or throw another log in the wood stove (I'm guessing an 1860s farmhouse still has a wood stove or fireplace. Or three.) And chances are, the amount of heat your system can produce will not be limited by the boiler, but the radiation (radiators, baseboard, etc.). You could have a nuke plant in your basement and still be cold if your radiation is not sized to meet the heat loss.

6) If you are getting 100-120k numbers out of Slantfin, and you plan to continue insulating and air sealing (with or without thermal IR and/or blower-door tests), then in your shoes I would look at gas-fired mod/con boilers in the 105k INPUT range. In no particular order, this would include brands like Buderus (GB-142), Burnham (Alpine), Triangle Tube (Prestige), Weil-McLain (Ultra), Lochinvar (Knight), Viessmann (Vitodens 100 or 200), and Munchkin. Of these, the Triangle Tube would be the first I'd look at. They have a 110 that would fit the bill quite nicely.

7) Now is also a good time to consider an indirect water heater. the 105k input size boilers will handle a standard 40-50 gal indirect without problem.

8) Don't forget the control strategy. The boilers above come with outdoor reset controls as a standard feature (except the Vito 100).

9) If all this seems daunting, don't sweat it. Plenty of resources here to help. It's also a lot easier these days to pick a boiler and control package than it was even a couple years ago. THE most important thing is to shop hard for an installer who knows his stuff and stands behind his work. There are many out there from which to choose, particularly in your neck of the woods. Be diligent. And patient.

Good luck!

 

Don't give up. It is your wallet these guys are playing with. I have done hundreds of heat losses in the last 15 years of the 30 I have been in this business. Thjey are padded by 15 to 25% so it is not going to be undersized even if you fininsh the third floor. I also have always choose the boiler from the DOE output and not the Net. Never had one too small yet. I find the problem when people do a heat loss and the boiler appears to be too small is it normally the piping not the boiler size.
Stick with a heat loss. I am sure you will find a competent contractor out there somewhere. I just had a guy yesterday which got two bids for a 150k unit. Did his heat loss and the home was 80,496. With 3 zones he will have an 80k boiler installed with no heating problems.
There are no shortcuts with fuel at $5 a gallon.

 

Hi Again Everyone,

Thank you all for your helpful suggestions and interesting comments!

In response to some of your remarks and questions:

1. I have baseboard heat.

2. Although I’m investigating it, I don’t think there is any way gas is going to be an option for me. Our farm house is almost 1000 feet back from the road. My initial inquiries with National Grid suggest that my share of the instillation costs for a gas line would be prohibitive. I’m still waiting for the final word on this.

3. As a result of the above, I’m looking at triple-pass oil boilers – Burnham MPO, Vissemann Vitrond. Any suggestions or recommendations regarding these or other oil boilers would be very much appreciated.

4. I like the suggestion made by Xiphias about doing a winter-time heat-loss assessment before replacing my boiler. However, I don’t think Razz or I would make it through the winter without a new heating system as the remainder of the family would kill us for trying.

5. I also completely agree with and am in complete sympathy with Plumbingods about the need to charge for thorough estimates. For whatever reasons, this sort of thing was never presented to me as an option by either of my (so far) two heating contractors. When I scheduled their visits to my home, both companies told me that a "heat loss estimate" would be performed by their contractors -- but, as I noted before, these estimates were just basic calculations based solely on the square footage of my home. Maybe the customers who are interested in spending some money up front for a detailed analysis in order to save money down the road are few and far between?

6. With this in mind I would like to ask: Does anyone have any suggestions about how I would go about finding and HIRING an experienced professional to come measure my home, windows, doors, etc., take into account my home’s age and insulation, and then give me a detailed, accurate heat loss estimate? If I could find a knowledgeable person to do this, and if that person’s heat loss estimate mirrored mine, this would give me the confidence that I need to move ahead with a smaller boiler than has (so far) been recommended. I'm at a loss as to where to start looking for this person.

Thank you all again for your help.

Charlie and Razz

 

I would think that any of the larger heating companies in your area would be able to send a representative to take all the proper measurements, Etc. But be prepared to pay for it. Ask questions before asking them to come out. And tell them exactly what you are looking for. Small companies may be able to help, if they have the time.

You could even ask the supply houses if they could help you out, but they usually ask you for the measurements and they usually figure a little high also. That is where I got my quick method.

 

Burnham MPO and Viessmann Vitorond are good stuff.

How about propane instead of gas or oil? Someday NatGrid will run a line past your house. Propane would have you ready, boiler-wise, to make the switch. The various modcons already mentioned can generally run on propane with a bit of adjustment.

What kind of baseboard? Cast iron, or the more modern copper tube with aluminum fins? (The cast iron is great stuff.)

Other than a "real" heat loss/energy efficiency company that would do blower door and thermal IR, getting a good heat loss is probably tough. You are looking for companies like this:

http://certifiedenergyconsulting.com/
http://buildingdiagnosticshelp.com/

only in your neck of the woods.

That said, however, two other options come to mind:

1) trust what you've done;
2) take some screenshots of what you did in slantfin-ware and see what others here think of the values, etc. Host them on photobucket.com or similar site. You might even include some shots of the building.

As said above, the 1860 vintage of the house makes this a bit less straightforward, but heat loss isn't rocket science. Get it close, find a good contractor who sells good equipment and does quality installs, and get it done.

 

I agree with the comments of all the others---you can't go wrong if you follow their advice.

Yes, old Yankee farm houses can be hard to figure for a heat loss---the construction tends to sprawl out & they were usually originally designed to be heated by fireplaces.

IMHO, at least 3 zones should be part of the new heating design--this will give you separate heat control of all 3 floors & you can leave the top floor at a50F until grandma arrives.

If it comes to buying an oil-fired boiler, remember that each model boiler usually has 3 sets of btu/hr output ratings based on what size nozzle is used in the burner---this allows ~a 40k btu/hr spread in heat range outputs that can be changed by just changing the nozzle.

For oil-fired 3-pass, I like Biasi B10, Slant/Fin Eutectic, Weil-McLain Ultra, and the Crown 3-pass.

 

Thanks for all of those helpful comments….

1. In response to a question from Xiphias: my baseboard is the copper stuff with aluminum fins.
2. Also, thanks for the suggestion about posting my heat loss calculations so others can check them over. However, my real concern is not that I screwed up the calculations themselves, but rather that I made some incorrect assumptions or failed to take something (or things) important into account – maybe something that a professional with some actual experience would immediately recognize. By way of example: the third floor of my house has eight dormers. I very much doubt that the sides or tops of these are insulated – maybe they are huge heat losers? The various heat-loss programs that I am using don’t seem to have any way of accounting for dormers. And perhaps there are other issues like this which, due to my utter lack of experience in this area, I am simply not recognizing. That’s why I am afraid to simply pick a boiler based on my own numbers.
3. In response to Dobbs: thank you for that interesting information – I did not know that it was possible to change boiler output by changing nozzle size. Is that why, for example, Burnham lists two heating capacities for each of its V8 series boilers? Are those outputs for different nozzles?
4. It looks, however, like using a bigger nozzle reduces boiler efficiency (I’m looking at the V8 specs again) – is that universally true, meaning is a smaller nozzle always more efficient (if it is feasible)?
5. Do all boilers have this sort of nozzle option? I ask because (unlike the V8) my Burnham MPO spec sheet only lists one heating capacity for each boiler size.

Dobbs mentioned heating zones, and, as it turns out, I’m in need of some advice about how to configure my heating zones with the boiler that lies in my future. Since this is something of a different topic, I’m going to submit a separate post on it. If any of you are able to help me with that aspect of things, I thank you ahead of time.

Charlie and Razz

 

I'm also curious about the boiler efficiency and nozzle size ratio. The general rule seems to be that one should size the boiler firing rate as close as possible to the heat loss rate. This makes sense (to me) with a mod/con or condensing boiler where little or no exhaust heat is produced.

However with a conventional or even a 3-pass boiler, it seems that a longer burn means longer sustained high stack temperature that has to be maintained to prevent flue gas condensation. In this case, it would seem (to me) that shorter more intense burns would be better because it minimizes the length of time the chimney needs to be at that high operating temperature.

Someone compared boilers to cars in that long steady runs are better and more efficient than lots of stop and go. But a boiler is not like a car. There is no enrichment mode in a boiler - the nozzle always sprays at the same rate whether it's hot or cold. It probably runs cleaner at a steady rate, but how is it more efficient?

 

ChazAndRazz,

Funky construction and old house would make me steer toward hiring a professional company to do the blower door/thermal IR test. If you're going to be in the house a long time and investing in it (insulating, upgrading, remodeling, etc.) it's worth it.

If the house heated fine with the old boiler(s), then you probably have sufficient radiation to meet the heat loss. You could also total up the number of feet of finned element (not just enclosure, but actual finned element), multiply by 500 to 600, and that would give you the amount of BTUs the radiation can put out assuming an average supply water temperature of 180F. (The 500-600 BTU/hr/ft figure is an often-used "standard" for fin-tube baseboard and it gets you in the ballpark).

Example: say you have 10 rooms and they each have 12 feet of finned element. 10 * 12 * 550 = 66,000 BTU/hr. So find a boiler in that range.

This method is more of a ballpark check on a real heat loss than something you should use to size the boiler. It does make some critical assumptions, namely that the building heats OK during the coldest periods of the year.

Also keep in mind that boiler performance, radiation output, heat loss calcs, etc. are all done with a pretty hefty margin of safety. rbeck mentioned ~25% and that seems about right.

What about propane? Is that an option? Using a gas-fired modcon with propane yields efficiencies much greater than even the 'high efficiency' oil-fired boilers.

 

Steady state wins the race. Cycling kills. Ramping up, only to ramp down when you're just getting going really kills combustion, stack temps, etc. Not to mention the wear on the other components in the system.

Take stack temperature. Many short cycles may never actually allow the stack to come to full temperature. The temp sawtooths below what it should be; you just get out of condensing temps and bang, the boiler goes off and you fall back and have to start over. A long, steady burn gets the stack to temperature and keeps it there.

Same with the thermal mass of a cast iron boiler. Getting it hot and keeping it hot takes less energy than heating/cooling/heating.

Oil fired combustion also takes a couple minutes to achieve steady-state. Gas is quicker (about a minute -- more like a gas stove). Point being long burns are better.

 

Hello:

I've seen references to a number of good three-pass oil fired boilers for hydronic heating systems, but no one has mentioned the System 2000. I've done mucho research on competing brands and system designs, and I'm convinced the System 2000, though pricey, is the most cost effective boiler over the longer term for my 2600 sq. ft. residence in New Hampshire, with expected payback of about 7.5 years.

I'd be interested in your opinion, thanks.

Airpilot

 

The System 2000 is the most efficient oil fired boiler when compared to other boilers when used to produce domestic hot water as well as heat, according to the folks at Brookhaven. Where the EK boilers fall short, in my opinion, is on two points. Those points are: (1) Durability. (Personal experience says they are about a 20-25 year boiler.) and (2) Parts such as chambers & controls (manager) are available ONLY thru Energy Kinetics meaning you have a sole supplier who can charge whatever he wants & you or your servicer can't shop eslewhere for parts. I work on them all the time & didn't put one in my own house.

 

Thanks, Grady. I think both your reservations regarding the System 2000 EK boilers are worth considering. The EK-1 does come with a lifetime warranty on the heat exchanger (parts, not service), and the burner is a standard item, using off-the-shelf parts, according to Energy Kinetics. Their computer is proprietary as you said, and would cost after its 5 year warranty was over.

In our case, we DO want to supply hot water as well as heat to our 2600 sq. ft. home in NH. We're likely to purchase the EK-1 and water heater, because we couldn't quite make geothermal calculations work for our home (max 120 degree heating water from 35 degree well water, meant marginal heating capacity and not nearly enough hot water capability), so we want to minimize our exposure to inflating oil prices as our second option.

Interestingly enough, whether I apply the Rule of 32 (2600 sq. ft. * 32 = 83200 btu) or the results of a heat loss calculation (taking into account our insulation, windows, door, floors, ceilings, etc), the results come up around 82000 - 84000 btu, which would mean, I think, a .6 mozzle on the EK-1F, which would then use about .68 gallon of fuel oil per flame hour.

However, none of these calculations take into account that we leave one of our three zones, the upstairs zone, off throughout the winter, except for a few days around Christmas when it's on for guests, and another of our zones, our bedroom suite, never exceeds 62 degrees except for an hour in the morning when it rises to 65 degrees. Our third zone, our downstairs living area, runs at 66 degrees in the daytime, and 62 degrees at night, and we supplement this with ceramic electric heaters as needed in the room we're working in.

None of the abovementioned actual operational parameters are taken into account when sizing a heating unit (ie: choosing a nozzle size). I believe that, in our case, we only really need about 55000 btu to comfortably handle our heating zones as they are actually utilized. This would use about 40% of the capability of the boiler, with a coresponding reduction in oil usage, I would think.

Does Energy Kinetics supply a smaller nozzle than the standard 83000 btu (.6?) one? If so, how small do they go?

Do you think a plan to undersize the nozzle to reduce oversizing and fuel flow makes sense? I guess my thought is, if the undersized nozzle is too small, it could always be replaced with a larger one...

Thanks for your help!

Airpilot

 

Check the EK warranty more closely. I think you will find it to be a pro-rated warranty. Ask your dealer for a copy of the actual warranty, foget the advertising. The fiber combustion
chambers seem to be a weak point in the System 2000. I would estimate "normal life expectancy" to be around 5-7 years, or so says my experience. One footnote to the statement about chambers: Nearly all the EK equipment I work on has Riello burners which EK no longer uses. That may or may not have a bearing on chamber life.

For the sake of the domestic hot water, if for no other reason, I don't suggest dropping the nozzle size below the minimum supplied by EK. You will probably actually end up upsizing from the low end.

 

I am a little confused as to why you think you would be marginal with geothermal.

I have a freind in NH who has geothermal, he installed in his home when he built the house about 3 yrs. ago and he loves it. I think he heats his hot water with a Super Stor water heater. His piping is run under his main parking lot about 5' below ground.
He owns his own heating company in Goffstown and I would be happy to give you his number privately so you could talk to him.

 

The "Rule of 32" is no way to figure a heat loss.

Geothermal is probably more in the picture than you think, if you do a proper heat loss, which can also account for the varying space temperatures and zones on/off.

Grab a copy of the free heat loss software at www.slantfin.com.

You can do a standard calculation, then modify it to change the indoor temperature so that you get the heat loss for the bedroom, and can run it again with a realistic space temp for the zones that are off most of the year.

Although that approach implicitly assumes the usage type (and therefore heat loss) of those rooms persists into the future, there is probably enough cushion in the heat loss to account for future changes (e.g., in 5 years the zone that currently is only used during holidays gets used all the time).

 

I went onto Slant Fins website to see if I needed to update my copy of the heat loss calculator, and it says the heat loss program will be available soon. Am I looking at the correct spot?

FYI - Watts Radiant Works also puts out a program for radiant heating design and they claim to have a heat loss calculator also.

 

Go here:

http://slantfin.com/heat-loss-software-order.html

fill out the form, make sure "download" is selected, and hit "submit." That will bring up a page with a clickable link to download the setup package.

 

Hi Plumbingods and All:

I'm concerned about the marginal capability of a geothermal system for my 2600 sq. ft. home in NH for two reasons:

1. My 30 year home presently uses 139 ft. of hydronic finned baseboard heating across its three zones. The average temp in these baseboards with an oil fired boiler is 160 - 180 degrees, whereas a geothermal system can only be expected to deliver 120 degrees. If I assume 500 btu / ft from the baseboards at 160 degrees, I get a calculated heat dissipation of 69500 btu. At 120 degrees, I would get 200 btu / ft, reducing the expected heat dissipation to 27800 btu, if, in fact, the baseboards will function effectively at that low a temperature. My heat loss calculations show a requirement for 60000 btu for a 70 degree delta, so you can see why I'm concerned about the capability of geothermal for my situation.

2. I can't understand how to design a domestic hot water delivery system based on a 120 degree geothermally heated water source. Clearly I can route 120 degree geothermally heated water into an indirect water storage tank like the Super Stor, but its recovery rate has gotta be terrible with only 120 degrees coming in. I'm hoping to get up to 4 gal / minute of 100 degree water from this tank on occasion.

Plumbingods, I emailed you off-line asking for the Goffstown contact you mentioned, thanks! Maybe smarter heads than mine can help me see how to do this!

Airpilot

 

The amount of radiation has nothing to do with heat loss. The old boiler operating at 160-180 does not mean that is what is required to heat the home. Have a heat loss done and determine what water temperature is required to heat at your OD design temperature. Here is a site that explains fairly well why to do heat losses and not worry about the amount of radiation.
www.comfort-calc.net/home-page.html
They also offer some piping diagrams and steam info.