Low Heat Condition

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Old 01-06-12, 12:27 PM
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Low Heat Condition

Hi,

I'm a newbie but I have a basic knowledge of HVAC and construction. I'm having a low heat condition in my apartment. Basically, the boiler is firing, the baseboard is getting hot, But not enough to heat the place on a cold day.

The basics:

Hydronic system with baseboard
Pennco furnace
Pressure is around 25 psi
The pump kicks in when the thermostat calls for heat
Temp is usually around 170, which is what the lower aqua stat is set to
I live on the top floor (4th) and the unit is in the basement
Only 1 zone

The problem:

Basically, From what I'm seeing, the thermostat calls for heat and it turns on the circulator pump, it doesn't automatically fire the boiler. The boiler only fires to maintain the low aqua stat setting. If I set the lower aqua stat to its lowest setting, it will pump around cold water, highest, it will pump around 220 degree water. This is wrong, correct?

So I'm thinking the switching relay? it's an Argo type(b218) that I can't find an exact replacment. I'm wiling to sit down with a wiring diagram and figure out how to wire in a new one, but I'm just not sure that's the route I should be taking.

Any ideas? I can't post any pics necessary, just didn't think this warranted it.
Thanks in advance
 
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Old 01-06-12, 01:02 PM
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What model is the aquastat on the boiler.?
It would seem that this is where the problem is, not the switching relay.

Peter
 
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Old 01-06-12, 01:25 PM
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The high aqua stat is a Honeywell L4006e with manual reset, The low, I haven't been able to determine the model, not written anywhere on it.

But I can get the furnace to kick on and off using the lower aqua stat, And the furnace to kick off using the high aqua stat. I figured this showed they are both working.
 
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Old 01-06-12, 01:31 PM
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You say apartment - are you a tenant? If so, call the landlord, this is not your problem.
 
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Old 01-06-12, 01:33 PM
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Ok , sorry, i'm lost.
The a'stats are working, the water is 170?
But not enough heat on the 4th floor?

Maybe there is air in the pipes up there and the water is not flowing very well.

Peter
 
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Old 01-06-12, 02:32 PM
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I've bled the system twice, It doesn't sound like there's any air in the system, I've heard what it sounds like to have air in the pipes and I don't hear that any longer.

So, yeah, I think the a'stats are working. If a put the lower a'stat down to say, 70 degrees, then when the thermostat upstairs calls for heat, It will turn on the circ pump and pump around 70 degree water. If I set the LO a'stat up to say, 200 degrees and let it reach that temp, then lower the HI a'stat to ~200, it will kick off the furnace. Once again making me think the a'stats are working.

But do ya see what I'm saying? The water never really rises above what I have set as the LO temp. As I understood it, The LO temp is what it maintains the water is the unit to, but when the thermostat upstairs calls for heat, It should rise to HI temp?
Am I understanding this correctly?
 
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Old 01-06-12, 03:12 PM
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You say apartment - are you a tenant? If so, call the landlord, this is not your problem.
FD, we need an answer to this before continuing, sorry...
 
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Old 01-06-12, 03:22 PM
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Condo, Individual heat and hot water.
 
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Old 01-06-12, 03:53 PM
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How did you bleed it?

In my house i sometimes get air up in the third floor.
There are no air bleeder caps up there.
No matter what i do, purge wise, via fast the fill down at the boiler i can not get the air out.
The only way to clear it is to use a high head pump, washing machine hoses and purge in and out of a bucket of water.
It's over 25 feet up there.


Peter
 
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Old 01-06-12, 04:44 PM
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I bled it by way of shut offs and hoses. By passing the pressure reducer. I don't believe there is air in the system, but either way, does the previously described condition sound correct? For the furnace temp to only work off the lower aqua stat and never get any higher than that?
 
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Old 01-06-12, 05:08 PM
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We need NJ Trooper to help us out here.
I'm not clear on how separate Limits typically work.
And i'm having trouble understanding how your system is working.
Maybe pictures might help after all.
My only recent experience is with tripple a'stats.
A call for heat on a tripple only works off the hi limit, typically with a fixed 10* differential.
If the temp drops below the low limit, the circulator will not run until it heats past the low limit differential. This doesn't sound like what you are describing.


Peter
 
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Old 01-06-12, 05:17 PM
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I'm not too familiar with with the triple aquastat either, but I know that there are certain rules you need to follow when setting the hi and lo. You need at least 20 degrees between the two. Try setting you high to 180 and lo to 160.

Check out Aquastats: Setting & Wiring Heating System Boiler Aquastat Controls, how to set the HI limit LO limit and DIFFerential dials on controls like the Honeywell R8182D Combination Control Aquastat
 
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Old 01-06-12, 05:50 PM
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The high aqua stat is a Honeywell L4006e with manual reset,
That high aquastat is a SAFETY device ONLY. That's why it has a manual reset. Leave that set at 200F. Don't attempt to use that to adjust the boiler temperature.

The low, I haven't been able to determine the model, not written anywhere on it.
Can you take pictures of it? we may be able to recognize it... upload pics to a FREE account at Image hosting, free photo sharing & video sharing at Photobucket and come back here and provide a link to your PUBLIC album.

does the previously described condition sound correct? For the furnace temp to only work off the lower aqua stat and never get any higher than that?
Yes, maybe... we'll know better when we see it.

Are you saying though that your boiler maintains the temperature at all times, whether there is a heat call or not?
 
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Old 01-08-12, 02:19 PM
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Ok, thanks NJtrooper, Didn't realize that. I kept seeing posts and websites and hi/LO/diff and I realize now that doesn't apply to this boiler. I don't know, maybe I do have air in the lines. All, I know is we had a recent cold snap and the boiler was firing but couldn't get the space above 55 degrees. I have a digital thermometer and I measured the temp of the copper coming out of the wall and it was about 95 degrees, not enough to do the job. What is the temp I should be seeing?




If you see anything, let me know, And once again, thanks for everyone's help.
 
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Old 01-08-12, 05:15 PM
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Yeah, that hi/lo/diff doesn't apply here...

As you now know, the one on the pipe on top of the boiler is a secondary hi-limit whose purpose is to cut off the boiler in case there's a problem with the other one and the boiler keeps firing. It's a 'redundant safety control'

The lower one is what controls the maximum temp that the boiler will fire to under normal operation, and if you have fin-tube baseboard it should be set to 170-180 or so.

Here's how this should work... and I'll get to why you might not have hot enough water up top in a minute...

Thermostat calls for heat and signals that to the Argo relay on the front of the boiler.

That Argo relay is what turns on the pump, and also tells the boiler that there is heat needed.

Boiler and pump run... boiler heats up and hits the limit on the lower aquastat, and the burner should shut off. If the heat call has NOT been satisfied, the circulator will continue to run and pump the hot water up to your apartment. During this time, the water will cool off... and when it cools appx 15 BELOW the setting of the lower aquastat, the burner will fire again... it will continue like this as long as the thermostat has NOT been satisfied.

When the thermostat satisfies, BOTH the burner AND the pump will shut down.

OK... that's that... now, why might the pipes up in your apartment be cold? Could be two, maybe three, things:

1. There isn't enough pressure in the system. (see below)

2. There is an air block in the piping.

3. The pump (or the Argo relay) is defective.

(or any combination of the above)

Your apartment is FOUR floors above the boiler. Let's say that each floor is 10 feet... that would put your radiators appx 40 feet above the boiler. To raise water 40 feet in the system, you need 0.431 PSI per foot, PLUS about 4 PSI of 'headroom'.

(you may understand some of this from your FD training?)

So, you need at LEAST 21-22 PSI in the boiler to raise the water to your altitude. Remember that this is the MINIMUM pressure when the boiler is COLD.

When the water heats up, you may see as much as say a 10 PSI increase in this pressure.

Normally, residential boilers have a 30 PSI safety relief valve on them. I'd like you to take a look all around your boiler for the relief valve. It will look something like this:


image courtesy quietelectronics.com

I think I can see the green tag on the left side of your boiler. Take a look at the tags on the valve and tell us what PSI your safety relief valve is set for. You may find that your boiler has a 50 PSI relief valve because you need more than 30 PSI due to being on the 4th floor. The dataplate on your boiler should also reflect the fact that the boiler is rated for 50 PSI operation.

Next, when the boiler is cold... tell us what the pressure gauge is reading, and the temperature that you are seeing at that time on the gauge.

Last thing to mention is that pressure gauges are lying sacks of poop. They can not be trusted. So eventually, if we can't get this solved by normal means, I'm going to ask that you verify the pressure gauge accuracy... we'll talk about that later.
 
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Old 01-08-12, 08:17 PM
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Wow, Thank you for your informative post, and I like the FD reference.

So I've noticed the gauge reads 20psi cold and goes to about 30psi when hot. The temp shows 170 when I hear the burners turn on, so this all just like you said.

Now, the unit says it is rated for 50psi and the relief valve is 30psi.
I haven't noticed any water on the floor in the times I've been down to inspect it.

Also, Is that expansion tank installed correctly? Seems to be upside down, but I'm no expert! Ha!
 
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Old 01-09-12, 03:38 PM
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...the gauge reads 20psi cold and goes to about 30psi when hot...

Now, the unit says it is rated for 50psi and the relief valve is 30psi.
I haven't noticed any water on the floor in the times I've been down to inspect it.
I wonder if someone may have swapped out that relief valve at one time and unknowingly replaced it with a standard 30 PSI part?

Also makes me wonder if the gauge is in fact accurate.

At 30 PSI, that relief valve should at least be drooling heavily.

So maybe the gauge is reading high and you only think you have enough pressure cold.

This would explain the low heat... if you don't have hot water getting up there, you sure won't have any heat!

Also, Is that expansion tank installed correctly? Seems to be upside down, but I'm no expert! Ha!
Yer right... I wasn't even lookin' at the tank in the pics!

Don't worry about that right now, that's minor. You probably will end up recharging it before I'm done with you though!
 
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Old 01-09-12, 03:45 PM
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Here's what MIGHT happen if you start 'fixing' stuff. You fix one thing and another problem comes up.

What is very possible is that you jack up the pressure in the system and then the relief valve starts spewing... either because you need to run at a slightly higher pressure than the 30 PSI 'standard', or because the expansion tank is in need of an air charge, and probably both.

I also want to mention that some localities have strict laws about un-licensed persons working on heating systems, ESPECIALLY in multi-family situations. Please check your laws and make sure you aren't breaking any!

First you need to verify the pressure gauge.

Then you will more than likely need to put a higher pressure relief valve on the boiler.

In all likliehood, your expansion tank will at the least need an air charge, and I'm pretty sure it could stand replacement, maybe the next size up even...

Ya know what? You might be able to keep that 30 PSI relief valve by upsizing the expansion tank to keep the pressure below 27 PSI when hot. You would still need to set the minimum at 21-22 (accurately! with a known good gauge) but if you could limit the pressure swing with a bigger tank, you might get away with it.

Are you in?
 
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Old 01-09-12, 07:55 PM
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I wonder if someone may have swapped out that relief valve at one time and unknowingly replaced it with a standard 30 psi part?
The boiler adjacent to mine is the same model with a 30 psi valve, and the building is 8 years old, so probably not. Oh, and don't assume the installers knew what they were doing, ha! The craftsmanship on this place is adequate, at best.

First you need to verify the pressure gauge.
Can I get a gauge to go on the spigot? Is there a standard pressure gauge I can ask for in a plumbing supply store?

Are you in?
Of course! I'll get the next size expansion tank and see how that goes.
Also, the unit doesn't have an air scoop, Think that's a good idea to invest in one?
 
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Old 01-09-12, 08:14 PM
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If the boilers are 8 years old, it would be a good idea to simply change the pressure relief valve as a matter of preventative maintenance. Since you will probably have to drain the boiler in order to change the tank, it would be a good time to replace that.

The LESS you have to drain to do the work the better. Notice that you have valves on the pipes leading to the apartment... CLOSE those and you won't have to drain the old system. The LESS fresh water you introduce, the better. You only need to drain the boiler down below the level you will be working at... don't drain it to the bone.

Please heed my warning about legalities...

Can I get a gauge to go on the spigot?
Yes... I use one I made from 'junk' parts.



Home Depot and Lowes places sell these:


image courtesy homedepot.com

But the problem with these is that the gauge is 0-200 (some are 0-300) PSI. That range is USELESS for the pressure we need to read. The fitting alone may be worth the $10 that they charge for this thing.

You can remove that gauge and pick up a 0-30 or 0-50 gauge at a real plumbing supply, or swimming pool supply house. Install on the fitting and go...
 
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Old 01-09-12, 08:15 PM
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the unit doesn't have an air scoop, Think that's a good idea to invest in one?
It's gonna be a bit of work to re-pipe to install. Probably not a bad idea... but see how it goes with the pressure gauge and tank first.
 
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