Troubleshooting Low Temperature in Boiler

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Old 12-29-12, 08:17 PM
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Troubleshooting Low Temperature in Boiler

I recently moved into a 100 year old house that utilizes radiant heating from a boiler in the basement. All of the piping for the radiators is galvanized steel 2" piping for the main pipes and 1/2" to 1" piping when it branches off. There are 2 zones (front and rear of the house) and 3 old style high volume/mass radiators attached to them. The boiler was updated ~8 years ago to a Laars Mini-Therm JVS 125,000 BTU and was attached to the galvanized piping (see attachments).

It has provided plenty of heat for the house but I was told by someone that it was supposed to be operating at a higher temperature. It was operating at 130 degrees F and about 5-10 psi (I've read some other posts and so I confirmed the pressure by a separate pressure gauge on the drain valve). I'm not familiar with this type of system so I downloaded the manual for the boiler but couldn't find nominal operating condition in it.

Since winter is upon me I hired an HVAC company to come tune it up and teach me basic upkeep for the system. They came out and measure the temperatures and confirmed it was 130 degrees F. They told me it was suppose to operate at 180 degrees F and 20-30 psi? When they shutoff the zones so the primary loop is the only path available it reached 180 degrees. When one zone is opened it would drop to ~155 degrees F and when the second is opened it dropped back to ~130 degrees F.

They told me some parts (Feed water inlet valve and resorber) were broken, everything was setup wrong, the boiler was to small and there was nothing they could do without major repairs. They gave me estimates and took off.

The next day I decided to try bleeding the system and there was tons of air in the system. It bled air until there was no pressure in the system. So I went down to the feed water valve and let more water in. The pressure went up to 20 psi... then I left more air out... added more water until it only bled water. Not sure why the HVAC guys didn't do this as part of the tune up but it started running a little hotter (~135-140 degrees) but its still running low.

The estimates they gave me were for adding a more defined primary and secondary loop (two pumps) or installing a new high capacity cast iron boiler (I think).

So since they didn't even bled the system during the tuneup I'm not sure I trust these guys. Is my system really sized incorrectly? Is it really built incorrectly? Any advice or thoughts? Thanks for any input!
 
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Old 12-29-12, 08:41 PM
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Can't comment on if the system is mechanically correct but the install looks pretty good.
Nice clean and neat job.

What is the condensate pump doing there ?
 
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Old 12-29-12, 08:57 PM
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Well, these guys just wanted to sell you a new boiler... profit mongers, every last one these days!

I don't see anything terrible with the setup, in fact I see a fairly decent job, INCLUDING the fact that the setup is "Pumping Away" ... which we'll talk more about in future...

told me some parts (Feed water inlet valve and resorber) were broken
If they are in fact broken, when replacing them, swap positions of the two components... the backflow preventer is to be installed UPSTREAM of the pressure regulator. What part are you referring to as a 'resorber'?

I don't think the boiler is too small.

That 1/2" line with the valve... that's a 'system bypass', open that valve all the way and leave it open. That pipe should have been much bigger by the book... we'll talk about this more later on.

Even though the guys only wanted to sell you a boiler, they may have been correct that a "primary/secondary" system would be a better choice for your system. From what I can see it doesn't appear that it would take much to make it so.

Yes, the temperature absolutely needs to come up, the boiler, flue pipe and chimney will be damaged if not. I hope it hasn't been running like that for a long time! How long has it been installed?

I'm a little concerned that it seems like the weight of all that piping and the water contained is being supported solely by the connections to the boiler. Is it? If so, I would recommend some supports to take the weight off the boiler connections. You need a little more than that single strap near the pump/tank.

Take some more pics... different angles, etc... if you can lose the cell phone and find a real camera, so much the better!
 
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Old 12-29-12, 08:59 PM
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What is the condensate pump doing there ?
If I hadda guess, it is to catch any discharge from the relief valve and the backflow preventer. I don't see a drain tube anywhere though.

If in fact that relief valve were to let out massive amounts of discharge, that poor little pump would be toast... but for small amounts it will keep the floor dry.
 
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Old 12-29-12, 09:00 PM
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What model Taco pump is that?
 
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Old 12-29-12, 11:38 PM
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Wow... lightning fast responses. Thank you so much!

These guys definitely didn't seem like they had my best interests in mind. To not even attempt to bleed any of the radiators during a tune up seemed pretty bush league to me but I just wasn't sure what they should be doing.

I'm not sure how to test the backflow and pressure regulator. By moving the tab on the pressure regulator to the vertical position it manually fills the system just fine but I'm not sure if that is indicative of a healthy valve. I'll have a look and see how difficult it'll be to replace or at least swap their positions.

Valve to the bypass is currently fully open... If I rebuild this system I'll widen that piping to match the rest of the piping around there. I'll also look more into adding that second pump only the secondary loop (outside the primary loop but before the junction for the zones). Is it just as simple as buying an additional pump? Or is there more logic to it such as the primary pump turns on first to get the operating temperatures up to nominal? I'm guessing that's the purpose of the primary/secondary loops... to maintain a more optimal temperature in the burner?

The flue pipe has some signs of corrosion at the joints from the water vapors. I don't believe it is too bad yet (no rust or anything) but the problem definitely needs resolution. I believe the system was installed ~8 years ago because when I purchased the house there was a record of work being done around that time. But in that 8 years I'm not sure how much service it has seem. I am unfortunately on the receiving end of 8 possible years of neglect by the previous owners.

You're right now that I look at it. There is just that one strap. I'll swing by HD tomorrow and pick up some supplies to remedy that situation. If only all these problems were that simple!

Now lets see if these attachments work!
 
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Old 12-29-12, 11:41 PM
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Taco - Cartridge Circulator
Model 0010-F3
HP 1/8
Amp 1.1
Hz 60
Volts 115
RPM 3250

That's pretty much everything on the label

And yes the condensation pump takes in the output from the boilder's backflow and the boiler's "PRV" pipe. It "pumps" anything in there to the drain across the house (in quotes because I'm not sure it works... Time for a test I suppose!).
 

Last edited by AdAstra; 12-29-12 at 11:50 PM. Reason: Answer Additional Question
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Old 12-30-12, 09:00 AM
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Take the cover off here. Whats it set at? Turn it up to 180F. It may be off so watch the boiler gauge and make sure the boiler kicks off around the 180f mark. Test this with a couple cycles of the boiler.


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It was operating at 130 degrees F and about 5-10 psi

That should take care of the temp. Now you need to boost the PSI up some. 12-15psi. This is the fill valve. It should maintain 12-15psi in the boiler when the boiler is cold. I cant see if there are valves before or after this device or whether they are open or not.

So you may want to check that. If all valves are open and that's all the pressure you get, then you can adjust that fill valve to increase the psi.




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Read the operation section here to familiarize your self with the fill valve. Also note the orientation of the fill valve and back flow. As Trooper stated it should be swapped.

http://s3.pexsupply.com/product_file...21-Install.pdf




 
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Old 12-30-12, 09:47 AM
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I'm concerned about what appears to be rust flakes in a pile behind the boiler under the flue pipe connection box.

Is that stuff falling out of the boiler somewhere? That's not a good thing if it is...


Turn it up to 180F ... That should take care of the temp.
Maybe... maybe not... with the volume of water that is in that system, and the way it's piped, it is very conceivable that it would fire for a VERY long time and not raise the boiler temp to setpoint.

That control may be an AUXILIARY high limit, and there may be another OPERATING high limit in the control box on the front of the boiler. As I recall, there is...

Looking at the pics again, it may not be quite as easy as I first thought to go with the primary/secondary setup, and it is NOT as simple as just adding a pump.

It may be possible to add a 'THERMIC VALVE' to the system to get things up to temp... needs to think about that...
 
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Old 12-30-12, 09:54 AM
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I cant see if there are valves before or after this device
When you do replace or swap positions (I would suggest replacing...) be sure to add ball valves on BOTH sides so that the valves may be easily serviced in the future... they are one of the higher failure items on a system.
 
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Old 12-30-12, 10:06 AM
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He has a system bypass. I would suggest for reduced labor, just shut that valve in the circle. Then install two tees here and pipe. It would then be a boiler bypass and the boiler should heat fast.

May be hard to do with that return valve, but throttle that valve on the return some to reduce the flow through the boiler.


trooper confirm?


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Old 12-30-12, 10:33 AM
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trooper confirm?
No.

The Laars boilers are copper tube heat exchangers and REQUIRE a system bypass to insure that there is proper flow through the boiler at all times.

Inadequate flow in these boilers can damage them beyond repair. Delta T across the boiler is one of the prime concerns.

If anything, that system bypass must be made BIGGER.
 
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Old 12-30-12, 10:38 AM
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Please see manual, particularly ppg 16-17

http://www.laars.com/LinkClick.aspx?...edownload=true
 
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Old 12-30-12, 10:41 AM
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Take the cover off here. Whats it set at? Turn it up to 180F


I believe the circled item is the emergency temperature shutoff or something? It is set to 200 Degrees F. Inside the front cover of the Mini-Therm there is another thermostat which I think is the desired operating temperature and that is set to 180 Degrees F.

If I turn off the zone valves and allow the system to just circulate through the bypass the system immediately rises to 180 Degrees F and shuts off (pump remains active and pumping) until the temperature drops down. Then it turns back on. So it seems under a light load it's able to operate properly.

If all valves are open and that's all the pressure you get, then you can adjust that fill valve to increase the psi
I did this an increased the pressure to 20-25 psi. I will drain it a little once it cools off to get to 15 psi if that is what you recommend.

Thanks everyone for helping!
 
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Old 12-30-12, 10:49 AM
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Is that stuff falling out of the boiler somewhere?


It appears so... I noticed it after I posted last night. It sits right underneath where the vent flue comes out of the boiler. Is it possible that the system is operating so poorly because the previous owners never serviced it and therefore could be damaged so bag it's just not capable of heating up this much water?

That control may be an AUXILIARY high limit, and there may be another OPERATING high limit in the control box on the front of the boiler. As I recall, there is...
Man you are good. You are absolutely correct I believe

 
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Old 12-30-12, 10:57 AM
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Please see manual, particularly ppg 16-17
Looks like my setup is identical to the "Multi-Zone Valve System" on page 16. And page 17 (Section 5B) explicitly calls out the need for a full sized by-pass valve in a "Multi-Zone Valve System" especially in systems sized 125kBTU and larger.

So this is starting to look like some major rework is needed!
 
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Old 12-30-12, 11:09 AM
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Interesting Troop... So ideally he would want to do P/S piping. last diagram bottom right in PDF. That would add the tees I described, eliminate the bypass, and add a circ to the return....

Does not look two hard to accomplish. there is plenty of room to add a pump and lower the return valve. Just get the tees 12" apart max.

Would doing that make that much more of a difference to what the OP has now? Anyway to adjust the valves with his set up?

It only shows how to adjust for P/S piping.

Oh and just throwing stuff out there. Not meaning to confuse the issue. I'll butt out.......
 
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Old 12-30-12, 11:15 AM
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I've been playing around with the zones this morning. Looks like if I turn one of the two zones (doesn't seem to matter which) the system reaches equalibrium around 160 Degrees F.

So in summary:
0 zones - 180 Degrees (just flow through bypass)
1 zone - 160 Degrees
2 zones - 130 Degrees

Should I turn off one of the zones for the time being and just use space heaters in the rooms that won't be heated? Or partially close some of the zone valves so that the system favors the bypass loop?
 
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Old 12-30-12, 11:18 AM
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Oh and just throwing stuff out there. Not meaning to confuse the issue. I'll butt out.......


We're all friends throwing out ideas
EVERYTHING is appreciated!
 
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Old 12-30-12, 04:08 PM
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We're all friends throwing out ideas EVERYTHING is appreciated!
That's a fact! Mikey knows that.

Is it possible that the system is operating so poorly because the previous owners never serviced it and therefore could be damaged so bad it's just not capable of heating up this much water?
Well... yes and no... I'm sure that lack of maintenance and correction of the low temperature condition didn't help anything, but even new I sorta doubt that the conditions would have been any different as far as the temperatures go.

The situation with the low temps would have been the same with ANY boiler of the same BTU rating.

One might think that the way to 'fix' the problem would be to just slap a huge boiler in and be done, but that's shooting oneself in the foot. Makes no sense... since there ARE ways to pipe the system such that the boiler is 'happy'.

ideally he would want to do P/S piping
Maybe... I'm kinda partial to the idea of using the thermic valve (Laars calls it a 'thermostatic union' I think...) One of the paragraphs in the manual speaks to that method. I need to look at that a bit more.

======================

The guys you had in said it was piped all wrong, and one of the things they may have noticed is that the boiler is feeding into and pulling from the 'bull' of a tee fitting. This is usually not recommended practice. It would have been much better if the installers had built manifolds where the boiler pumped into and returned from the ends of the manifolds, with the piping to and from the system on the 'bulls' of the tees. It just flows a whole lot better for one thing. Imagine the turbulence and resistance that water sees as it is pumped headlong into that copper wall in front of it, and then has to turn and split in two directions.

If you are going to go to the trouble of re-piping anything, I would recommend that be changed at that time.

Here is an example of what I'm trying to describe:



Also, in a heating system it's always advantageous to minimize resistance to flow. One way it to always use 'long sweep' or 'long radius' elbows. They don't take an abrupt "right turn Clyde", instead they 'sweep' around the bend. Yes, they cost a little more, but they flow better... and that's what we want in a heating system.


image courtesy delafleur.com
 
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Old 12-30-12, 04:30 PM
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There are definite drawbacks to a system bypass setup.

The biggest is that it can lead to uneven heating in the home.

The reason for this is that flow through the system is drastically reduced in order to maximize flow through the boiler. This means that the 'delta T' between the water going to the rads and the water returning from the rads will actually be INCREASED, because the slower moving water will shed more of it's heat before it returns to the boiler.

This is NOT what we want to do.

Yes, it protects the boiler but at the expense of a less responsive and sometimes problematic (unbalanced) heat delivery to the home.

Enter primary/secondary piping.

The proper flow through the boiler is maintained at all times by the pump on the secondary boiler loop.

The proper flow through the system is maintained by the pump on the primary system loop.

The boiler 'injects' it's heated water into the system loop via the closely spaced tees.

BUT... there's still a problem with this approach.

It is STILL POSSIBLE that the return water to the boiler will be cooler than it should be and the delta T across the boiler greater than manufacturers recommendations.

This would be the case if the flow in the system was GREATER THAN the flow in the boiler.

NONE of the hot supply from the boiler would make it's way back to the return of the boiler and help to reduce the delta T.

In this particular system, there is a HIGH probability of this being the case.

There needs to be a solution that addresses ALL of the issues... System flow must be maintained, Boiler flow must be maintained, AND the delta T across the boiler must be within manf specs.

How do we do that?

See section 5 D and Figure 11 in Laars manual.

With the thermostatic union installed, when the system and boiler are cold, the flow will simply recirculate through the system, and also recirculate through the boiler until such time as the boiler supply gets to 140. Then, the thermostatic union will begin to open and allow hot water into the system. It will 'modulate' it's opening to protect the boiler by keeping it hot (system bypass), but the heat that IS injected into the system makes it all the way around the loops because it's flow is not being restricted due to the primary secondary setup.

This method meets all three of the requirements above.

There are other thermostatic devices that can be used. Esbe makes a 'three port' device that achieves the same function. One could also use a 3-way motorized valve with appropriate electronic controller ($$$).

Here is the submittal sheet for the ESBE (Danfoss) thermic 3-way valve.

http://s3.pexsupply.com/product_file...-Submittal.pdf

For your system I would choose the 140 1-1/4" model (I believe you currently have 1-1/4" copper to and from the boiler?) and mount it in the return side.

This submittal doesn't show the 'balancing valves', and in fact they aren't absolutely needed. You WOULD want to add valves that would allow servicing of the boiler... for isolation purposes.
 

Last edited by NJT; 12-30-12 at 04:55 PM.
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Old 12-30-12, 11:39 PM
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The reason for this is that flow through the system is drastically reduced in order to maximize flow through the boiler.
Would this also apply to partially closing the zone valves (say 45 degrees / 50%) such that the flow favors the bypass? I tried it just to see and noticed it takes a while but the operating temperature goes up a little. I'll have to keep testing it to see how well it continues to heat the house. Is this a possible temporary fix until I can do more major work when the weather warms up? Do you have a recommendation on a gadget to determine the temperatures in the pipes? I've been having to bleed water out of the system and use a $2 cooking thermostat to check the temps. Although I can't check the temps on the output side of the boiler to check the delta Temp (plus I'm not sure I trust the built in thermostat).

I believe you currently have 1-1/4" copper to and from the boiler?
I measured the OD of the pipes and this is what I got:
Main copper loop - 1.375"
Bypass pipe - 0.875"

...thermostatic union...
I like this. Reminds me of the thermostat on my cars. Valve pops at a predetermined temperature once the coolant around the engine heats up (ironically to 180 deg F... I see a pattern).

If you are going to go to the trouble of re-piping anything, I would recommend that be changed at that time.
It definitely sounds like I will be doing a bunch of re-piping... Thermostatic union, update the junctions so they don't run into the bulls, possibly another pump, building a new manifold? I noticed you linked to a PEX website. Would this be an opportunity to re-pipe my whole house with PEX tubing (all my pipes are easily accessible in the basement). Could be an opportunity to reduce the volume of water in the system since the majority of the piping is 2+ inch galvanized steel piping. Plus they wouldn't hang down 12 inches from the ceiling and hit my head! Also... thoughts on reusing copper fittings? Stopped by HD tonight and each of those 1-1/4 fittings are $15!
 
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Old 12-31-12, 07:44 AM
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partially closing the zone valves (say 45 degrees / 50%) such that the flow favors the bypass?
Sorry, I meant to answer that question before...

You can attempt to 'modulate' the valves if you like. A few points to mention:

Yes, the same drawback exists. Slow the flow in the system to any significant degree and the first rads in the loop will be much hotter than the last rads in the loop because of the heat shedding that occurs.

In ANY system the return water comes back cooler (standard design is to go for 20F delta). If the flow is too lazy, more heat is shed from the water and it cools more as it goes around the loop, returning to the boiler much cooler, and causing cooler rads at the end of the line.

Trying to 'modulate' a ball valve is difficult. Closing the valve 'halfway' does not result in half the flow. It is not a linear relationship. It's logarithmic... the first half of the closing results in very little flow reduction. Probably 80% of the flow reduction occurs in the last 20% of closing. It's VERY touchy... small movements at nearly fully closed make huge differences in flow, while large movements over the first 80% of the range make little difference.

Main copper loop - 1.375"
Bypass pipe - 0.875"
Yes, 1-1/4" on the main...
and 3/4" (not 1/2") on the bypass.

Reminds me of the thermostat on my cars.
Exactly... I like automotive analogy.

The earliest models of the ESBE DANFOSS valve that I linked to actually used what appeared to be nothing more than a standard automotive type thermostat. The design has evolved significantly.

Would this be an opportunity to re-pipe my whole house with PEX tubing
I suppose that it would... but understand that what you are contemplating is a HUGE amount of work, and it must be ENGINEERED properly. There's more to it than simply cutting out pipes and replacing with PEX. One must take an overall SYSTEM view and approach to doing this. All sorts of things need to be considered, not for the faint of heart!

If you are from an Engineering discipline, (or even a bright layman) and want to learn about hydronic heating, the 'bible' is a book by John Siegenthaler; "Modern Hydronic Heating" THIRD EDITION (if you spend the bucks (it ain't cheap!) might as well get the latest ed. There are still a lot of the 2nd edition for sale on the web, and not much cheaper than the latest one)

thoughts on reusing copper fittings?
I've done it, I won't lie.

It's not easy. The fittings are difficult to clean so you can get them back together. One little solder bump left inside and it won't go onto the pipe. If you try to 'melt' them back into place you will end up with leaks all over the place and plenty of burnt fingers (I've done that too!).

Whether or not you decide to reuse fittings sorta depends on how much your time is worth to you. Say you decide to 'pay' yourself ohhh, $25 / hour ... it could take a half hour to clean a fitting so you can reuse it. Do the math.

There is also the question about whether all that extra heat used to clean the fittings weakens the copper or not. I don't know that it does, just throwing it out for consideration.

Yes, they are expensive, no question about it. Buy online and save about 30% over big box store prices.

Example, you would probably pay at LEAST $10 for this at Lowes or HD

WP7LT-20 - Cello WP7LT-20 - 1-1/4" CxC 90 Long Turn Elbow
 
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Old 12-31-12, 11:46 AM
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Slow the flow in the system to any significant degree and the first rads in the loop will be much hotter than the last rads in the loop because of the heat shedding that occurs.
There's more to it than simply cutting out pipes and replacing with PEX
I felt this was a good opportunity to post a schematic of the piping in the house. Main piping is 2 - 2 1/4 inch galvanized steel piping. All of the branches are smaller but I have yet to measure their OD's or lengths. I think there is ~ 32ft (64ft for both) of the large galvanized pipe in zone 1 and also 32ft (64ft for both) in zone 2. I'll post an update to this once I measure everything but I thought I'd throw this out there for now.

Since there is just a main reservoir that the radiators tap into (parallel and not in series) does this make replacement any easier? And since they are tapping into that reservoir couldn't I just make the reservoir smaller (just down to a manifold) and have the lines from the reservoir to the radiators be longer?

Thanks again for all of the help! This is truly amazing!

Note: I have tried to make the radiators in this diagram proportional to each other similarly to how they are in real life.
 
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Old 12-31-12, 03:56 PM
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Main piping is 2 - 2 1/4 inch galvanized steel piping
It doesn't look like galvanized to me. From what I can see it's what we call 'black iron' pipe, even though it's steel, not iron, no galvanizing. I don't know why we call steel pipe iron... just one of those things I guess!

Your system is what is called a "2 pipe, direct return" arrangement.

Are there any 'balancing valves' on each of the rads? (or on the pipes to and/or from them?)

With a direct return system the first rads on the line can sometimes have a tendency to 'hog' the flow which results in the rads further down the line not getting enough flow (and running cooler).

Sometimes the dead guys who designed these systems would compensate for this by using smaller pipes off the mains to the first rads, gradually increasing the size toward the ends of the runs in order to try and achieve equal flow in each of the branches. Throttling valves on the rads are a better choice IMO. Leave the end of the line valves all the way open and gradually close them the nearer to the boiler.

There is a scheme called "2 pipe, REVERSE return" which addresses this issue by making the runs to and from each rad equal length.


image courtesy tpub.com

Figure A is 2 pipe, reverse return.
Figure B is 2 pipe, direct return.

If you trace the path to and from the boiler to each rad and back, you will see that with reverse return, all distances are the same. There exists (more or less) equal pressure drop at the supply and return of each branch, resulting in (more or less) equal flow through each rad.

Direct return obviously has progressively longer paths the water needs to follow, which results in progressively less pressure difference between the supply and return to each rad because of the pressure drops in the piping.

I say all this up front because if you DO decide to replace the piping, I would urge you do do a reverse return.

more...
 
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Old 12-31-12, 04:14 PM
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Replacing the piping WILL reduce the water volume, and WILL help 'fix' the problem, but do understand that you will still have a high water volume system because of all the water in the cast iron rads. You will still need to incorporate the 'boiler protection' measures.

Something that will also help... not a GREAT deal, and may cool the basement a bit, would be INSULATING the pipes.

OK, now that that's all said;

If you think that $15 is a lot of money for a copper pipe fitting, check out the pricing on the adapters you will need to adapt to the piping to and from the rads... then, you need to either rent or purchase the tools to make the proper connections to those fittings... and while cheaper than copper, PEX of the size you will need is not going to be cheap either.

You will need at LEAST 1" PEX tubing, and I would recommend using PEX-AL-PEX. I would be more comfortable suggesting 1-1/4" for your application, but to my knowledge the largest size you can get is 1"

If you go reverse return, you will probably need at 200' of the 1" to do the job. Figure on about $300 for the tubing.

Are all the rads connected to the main lines with black pipe also?
 
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Old 12-31-12, 04:18 PM
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Troop, if the OP when to all that trouble should he just replace the rads with BB and run all 3/4????
 
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Old 12-31-12, 04:21 PM
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Another tubing that would be easier to work with, is "ONIX" by Watts... but it's pricey. 200' of the 1" and you're looking at probably $850 or so.
 
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Old 12-31-12, 04:24 PM
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just replace the rads with BB
I would never suggest that.

Radiators are a VERY comfortable form of heat. I wish I haddem in my home!

If and when a boiler replacement is due, cast iron rads lend themselves to modulating/condensing applications beautifully!

A 100 year old home, I would want to retain as much of the 'character' as I could.

But yeah, that's a possibility.
 
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Old 12-31-12, 06:24 PM
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So I experimented with adjusting the zone valves (with the bypass completely open) and the entire system gets up to temperature finally! Small win and still a long ways to go I know but I thought I would share and thank you again. Seems like the all of the radiators are putting out plenty of heat. I will add that this happens when I'm "testing" and cranking the heat. I'll need some time to see how well it's working during standard operations.

Something that will also help... not a GREAT deal, and may cool the basement a bit, would be INSULATING the pipes.
I was one step ahead of you on the insulation! Great minds think alike! During my stop at HD yesterday I picked up some pipe insulation and wrapped a couple of them. Partially in hopes of reducing heat loss in the pipes and partially because as I'm getting this thing to run hotter... I was getting more sensitive to accidentally touching the pipes!

Replacing the piping WILL reduce the water volume, and WILL help 'fix' the problem, but do understand that you will still have a high water volume system because of all the water in the cast iron rads. You will still need to incorporate the 'boiler protection' measures.
Copy that. I wouldn't dream of updating to PEX or something newer for the main piping and not redo the maze at the boiler or do plenty of planning It was more of a "if I'm doing the boiler protection measures, why not do the rest" thought. It'd be nice to not have those huge pipes hanging throughout the basement too!

Radiators are a VERY comfortable form of heat.
A 100 year old home, I would want to retain as much of the 'character' as I could.
So so true. When I moved in I was skeptical but I can't imagine not having it. And it is definitely part of the charm. When I finish the basement I would like to use them as well (I have 1-2 unused ones sitting around). If my boiler can't handle 2 more high volume (mass?) radiators then I might think about newer low mass baseboard heaters but until then I'm going to try to keep it as original as possible (understood that finish basement and original don't go well together but we'll see about that).

Are all the rads connected to the main lines with black pipe also?
Indeed they are! The 2" iron (thanks for the correction!) main pipes feed varying sized connector pipes. I tried to show the proportional sizes on the last schematic I uploaded. I have put the OD's of the iron pipes on the diagram below. Hope it helps explain a little more of this puzzle!
 
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Old 12-31-12, 07:25 PM
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So i was looking at the emergency cutoff for the system. I believe this is a backup in case the boilers temperature control fails so the the system doesn't get to hot and to high of pressure. From the cover its a Honeywell Aquastat L6006C.

http://s3.pexsupply.com/manuals/1350..._PROD_FILE.pdf

I can't seem to understand from the manual what the "Differential Adjustment Wheel" should be set at. It's at 5 right now... The manual mentions that it's a differential between the desired temperature and the room temperature? Any ideas?

Happy New Year if I don't get back on tonight!
 
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Old 01-01-13, 10:21 AM
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I can't seem to understand from the manual what the "Differential Adjustment Wheel" should be set at. It's at 5 right now... The manual mentions that it's a differential between the desired temperature and the room temperature? Any ideas?
I'm not sure what you saw in the manual... page? paragraph?

Differential in any aquastat is a 'hysteresis' built into the control.



The diff is the distance between the two vertical lines. This chart could be flipped also, which would be more appropriate to the aquastats we use, if one considers the HIGH end to be ON...

If this differential were not built in, as the control approached setpoint, the control would 'chatter' on/off/on/off at that point.

The amount of diff that is needed varies from application to application. In the case of an auxiliary high limit, you don't want MORE than the standard operating control provides, otherwise the aux control would assume command because it wouldn't switch back on until the temp was below the desired range of the operating control.

IMO, the aux high limit should be a MANUAL reset, but many are not. Some inspectors care, some don't. The idea of a manual reset is that if there is a PROBLEM that the aux limit is controlling, the operator should be somehow alerted. No manual reset and one might not realize there's a problem for some time.

Bottom line, a diff of 5 should be fine, and the setpoint needs to be above the setpoint of the operating control inside the boiler by about 20 to avoid 'nuisance' tripping.
 

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Old 01-06-13, 09:49 PM
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Sorry I've been absent for a little while. The new year has been a little hectic.

Things seem to be working better I think. Still not the way I'd like them however I don't think that will happen until I can find an opportunity to add the modifications we discussed so far

Right now if the thermostat calls for a large heat jump (thus the system operates for a while) it slowly does heat up the operating temperature to a better temperature (Max 170+ degrees I think). However if the thermostat is just maintaining the house temp I don't think the boiler gets water above 150 degrees. Also something I have noticed is that the Delta Temp (Even when using just the bypass) between IN/OUT of the boiler is usually 8-10 degrees. Does that indicate that the flow rate is too fast through the heat exchanger?

With the thermostatic union installed, when the system and boiler are cold, the flow will simply recirculate through the system, and also recirculate through the boiler until such time as the boiler supply gets to 140


I was going though some of the upgrades we have discussed. I was thinking about the Thermostatic Union and wondered why you recommended the 140 Degree Union? I thought it was bad when the system operates at ~130-140 degrees. I'm assuming this union would go on the OUT side of the boiler (see attached image) so that once the primary loop gets to the desired temperature of the union it starts allowing colder water from the secondary into the primary loop? Or would it go on the IN side and attempt to maintain a IN temperature of something in the high 150 degree range (so the OUT rises 20 degrees and is in the high 170 degree range?
 
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Old 01-07-13, 07:24 AM
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On the return side is where you would want the 140 valve, but not at the closely spaced tees as you have indicated. It would be similar to the bypass loop you have now, between the supply and return to the boiler, on the boiler side of the CSTs, on the system side of the boiler loop pump.

I'll rework your drawing this evening to show the location.

By maintaining the RETURN at 140, above the condensing point, the boiler is protected. If placing the thermostatic device on the supply side, you would want a higher temp device...
 
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Old 01-07-13, 06:00 PM
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Here's a few changes and notes:

When there is a heat call both pumps will start.

If boiler is below 140 at return, almost all flow in boiler loop will 'recirculate' through thermostatic tee.

When boiler is hot, ThermoTee will begin to open and modulate, allowing heated water to circulate in system, while protecting boiler from cold return.

As system heats, ThermoTee will open more and more until fully open, or heat call ends.

Boiler is protected at all times, manufacturer required flow is maintained in boiler, full flow always exists in system to evenly distribute heated water.

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