"Sticky" suggestion

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  #1  
Old 11-12-12, 07:09 AM
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"Sticky" suggestion

What is the normal sequence of operation of a hot water baseboard system?

It sure would help me understand how the system works if I knew in what order the various events occurred.

(Mine is a 1994 Hydrotherm installation but I'm hoping the sequence is similar for all)
 
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Old 11-12-12, 10:40 AM
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That might be a tough one as each system or method of working (location or date installed) will impact the way things are connected.
 
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Old 11-12-12, 12:18 PM
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Isn't there a general sequence that would be taught in HVAC school?
1 - thermostat calls for heat.
2 - gas valve opens.
3 - circulator pump starts.
4 - hot surface ignitor glows.
5 - fire department arrives.

(just seeing if anyone's paying attention...)
 
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Old 11-12-12, 03:25 PM
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Hi Guy, I've thought about this over the years and came to the conclusion that it's just too much to try and take all the variables into account, as Northern Mike has pointed out.

I mean, you've got older systems with millivolt gas valves, systems with standing pilots, systems with spark ignition, with hot surface ignitors... there's blocked vent switches, rollout switches, different aquastats, and the list goes on and on and on and on...

The other reason is that by having the posters ask their questions we get a chance to assess their own skill sets and make appropriate suggestions. If we put some 'generic' "How It Works" up there, people just might get themselves in trouble... and we might be liable... and have to pay the fire department, and lawyers, and insurance companies, and God forbid, survivors.

Thanks for the suggestion though!
 
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Old 11-12-12, 08:35 PM
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Ok fine. Then for my system is this the basic order?
Thermo calls for heat.
Gas valve opens & standing pilot lights flame.
Water temp Low point is hit.
Circulator pump runs.
Thermo is satisfied & gas shuts off.
Pump stops (?)
 
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Old 11-14-12, 08:57 AM
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Insert in there somewhere "Flue damper opens".
It doesn't work (always open), so I don't know at what point it's supposed to open.
 
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Old 11-14-12, 02:36 PM
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Guy, we don't need to 'bump' here... we get to it when we get to it, if we get to it...

My eyes can't focus on that label pic well enough to read it and even if I could, it still won't tell me enough without knowing what exact controls are installed on your boiler.

Do you know what aquastat is installed?

Do you have zone valves?
 

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  #8  
Old 11-14-12, 02:42 PM
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My eyes can't focus on that label pic well enough to read it
It is hard to tell from the pic provided. Could be model # HC-100E-V. If so, then:

http://hydrotherm.com/modules/lit_li...litFileID=1550
 
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Old 11-14-12, 03:12 PM
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And it appears that the operating sequence is spelled out in the manuals on the electrical diagram pages...

So look at that first Guy and come back with any add'l info or questions.
 
  #10  
Old 11-15-12, 06:26 AM
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Basic boiler operation

Yes HC-100E-V. Thank you Rockledge for the link. My manual is 200 miles away.

The circulator pump & gas valve operation aren't even mentioned in the operating sequence in the manual. Looking at the schematic (standing pilot, L8148E aquastat, no zones) I see there's no low limit and the circulator runs as long as the thermostat is closed. On long run times the burner bounces off the high limit until the thermostat opens.

What do these 2 boxes do? There's nothing in my manual folder for these.
 
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Old 11-15-12, 07:55 AM
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You sure thats the # on the aquastat?

The aquastat has a preset differential. I believe @ 15f. If that aquastat has a min temp of 180f thats where I would set it. Thats the lowest setting.

On a continual call for heat after 180f has been reached and the burner kicks off, the burner should kick back on @ 165f.

The black box is the control for the circ.

But that looks like a strap on aquastat. Possibly an additional hi limit. No aquastat at the front of the boiler? Take more pics...


http://www.pexuniverse.com/docs/pdf/...lays-L8148.pdf
 
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Old 11-15-12, 09:53 AM
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The black box (the one labeled "Level Control") does what for the circulator? I would have thought the grey one with the temperature adjustment might have something to do with the pump just below it.



You sure thats the # on the aquastat?
No, that's the number in the manual linked in the earlier post. I don't know which aquastat I have but it is in the front and this is the insides:
 
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Old 11-15-12, 11:05 AM
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I believe that the 'black box' is a LOW WATER CUT OFF (LWCO) and will shut the burner down in the event that water goes low in the boiler.

Chances are that the small gray aquastat is an 'auxiliary high limit' and if so should be set ABOVE the normal 180 setting of the larger Honeywell aquastat by perhaps 20-30 degrees F .

It is POSSIBLE that the smaller aquastat is a LOW TEMP control for warm start of the boiler... or possibly a 'REVERSE AQUASTAT' to hold the circulator off until the boiler reaches a preset temp.

In order to tell which it is one would have to trace the wiring or be familiar with how the boiler normally operates.
 
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Old 11-15-12, 11:06 AM
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If the black box is mounted to a probe that is inserted into the pipe behind it, then's it's probably a low water cutoff (LWCO) safety control.

Edit: Looks like Trooper agrees...
 
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Old 11-15-12, 11:10 AM
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Chances are that the small gray aquastat is an 'auxiliary high limit' and if so should be set ABOVE the normal 180 setting of the larger Honeywell aquastat by perhaps 20-30 degrees F..
I thought that too at first glance, but then I noticed that it's mounted on the return piping, which is no place for a high limit safety.

 
  #16  
Old 11-15-12, 12:07 PM
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Originally Posted by NJ Trooper
In order to tell which it is one would have to trace the wiring or be familiar with how the boiler normally operates.
I am trying but it's coming bit by confusing bit instead of all at once like I had hoped in the first post. I assumed this was a typical hot water system assembled with common name-brand controls that anyone with experience would recognize & could explain. I'm very familiar with furnaces having maintained several of my own over the years but this is my first hydronic system and they're certainly not as "integrated" as the typical furnace is.
 
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Old 11-15-12, 12:24 PM
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take the cover off that small aquastat and tell us what the temp is set for...and where do the wires to it attach?
 
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Old 11-15-12, 02:42 PM
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I assumed this was a typical hot water system assembled with common name-brand controls that anyone with experience would recognize & could explain.
Of course... but before explaining anything, we need to know everything! If we were there to poke and prod and examine, in about 5 minutes you would have your answer but across the internet we need to ask questions, wait for answers, etc... in order to know exactly WHAT controls are mounted and then figure out WHY they are mounted... stuff like that.

The picture is getting clearer though.

Once we know what the small aquastat is wired to we should be able to tell you what's what whit yer berler.

Thing about system is, they are not all the same. And they are 'organic' in many cases. They 'grow' over time. It's very possible that when your system was installed, it did not have that LWCO and extra aquastat. May have been added due to some 'code requirements' at a later time... or on some boiler techs 'whim' of an idea that someone needed some extra control... and they got paid a commission for 'upselling' the customer. Or ... ? ... sometimes we just can't know everything!
 
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Old 11-15-12, 02:53 PM
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Let's do this, a bit by bit at a time:

Your main aquastat... if the LWCO and extra aquastat were not installed... since you have no zones...

Thermostat is wired to the T T terminals. When thermostat calls for heat:

IF boiler is below high limit setpoint, AND circulator is wired to C1 C2 terminals,

THEN relay in aquastat pulls in which turns on circ and (if it was working) would send signal to vent damper to open.

When vent damper opened and activated it's ENDSWITCH, that endswitch would send signal to burner that it was OK to fire.

Main gas valve would open, burner would fire, hot water would pump to rads.

If thermostat is satisfied before high limit is hit, the whole thing would simply shut down. Burner off, circ stopped, damper would close. System would wait for next heat call.

If high limit is hit before thermostat satisfies, BURNER would stop, damper would possibly stay OPEN (or it may close depending on how wired), but CIRCULATOR would continue to pump.

If thermostat satisfies before high limit drops below the DIFFERENTIAL setting, circulator would stop, and damper (if still open) would close (after built in delay in damper circuit... about 2 minutes or so).

If thermostat does NOT satisfy before HL drops below DIFF, if closed, damper would open, burner would fire, circ would continue to run.

Lather rinse repeat until thermostat satisfies and boiler shuts down for nap time.
 
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Old 11-15-12, 03:03 PM
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LWCO is pretty simple... if water is low in boiler, thermostat can still call, pump will still run, damper may still open, but burner will NOT fire until cause of low water is remedied.

By the way, it's somewhat unusual for that to be mounted on the return. I don't see any reason why it would not still function as it should, but we usually see them on the supply.

The small aquastat... hmmmm... yes, it is mounted on the return... strange...

IF it were mounted on the supply, I could see it being an auxiliary high limit. In this case, if the main aquastat were to fail and not shut the burner down, that aux HL would step in and do so. Some aux HL are manual reset requiring a push of a red button on the front. Yours doesn't have one. But I don't think mounting on the return makes sense for aux HL anyhow.

In fact, none of the possible uses I mentioned earlier post really make much sense with it on the return, so before going further we need to know where it's wires go. Do tell, please.

While I got ya on the line, you said:

I don't know which aquastat I have
Isn't there a paper label pasted on the inside of the cover?
 
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Old 11-15-12, 03:43 PM
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Looks like a white rodgers aquastat to me.

 
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Old 11-15-12, 04:02 PM
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I agree on the small one... to clarify...

This is the one he didn't know though:

I don't know which aquastat I have but it is in the front and this is the insides:


Almost certainly an L8148E of some flavor.
 
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Old 11-15-12, 04:30 PM
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Yes post 11 I put a link.....


http://www.pexuniverse.com/docs/pdf/...lays-L8148.pdf


I am wondering if that aquastat is wire to hold the gas valve off.??? I see the wire going to the front of the boiler.

Other thing where does that t stat wire from the LWCO go?
 
  #24  
Old 11-15-12, 05:03 PM
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Well if you really need the wires traced, even more pics, etc then we're done because as I've said this is 200 miles away and this thread will be buried & forgotten long before my next trip.

As for the Tstat wire I suspect it only runs through the box & conduit on its way to the L8148. To the best of my knowledge of the previous owners this cottage was never used in winter beyond hunting season. The system is 18 years old but "low miles" and there's no evidence it's ever been serviced since installation.

I think I have a pretty good grasp on what everything does--if not quite how it does it. For instance the low water control--the boiler is in the basement and the baseboards are upstairs. Just HOW would that thing know if the water is low since the entire system would have to be nearly empty before that control got dry.
 
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Old 11-15-12, 05:04 PM
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If you're 200 miles away why do you care what the boiler does then?

ust HOW would that thing know if the water is low since the entire system would have to be nearly empty before that control got dry.
Exactly.

Note that the probe is above the level of the top of the boiler. It won't shut off until the water is that low, and since it's there as a safety device to prevent the boiler firing dry, it will perform it's intended service just fine in that position.

It doesn't care that there's not enough water in the system to heat the home, only that there's enough in the boiler to prevent a meltdown and possible catastrophic fire.

If you're concerned about the place going cold and freezing the pipes, there's other devices that perform that function... some will dial a telephone number, some will send an email, etc... google and ye shall find.
 
  #26  
Old 11-16-12, 08:04 AM
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If you're 200 miles away why do you care what the boiler does then?
Are you serious? That's almost as insulting as the "IF we get to it" comment in post #7.

Those options aren't available there. Besides the fact that they alert you to a problem that's already happened and prevents nothing.

I'm here to learn and understand a type of system that's new to me and prefer that I do this BEFORE I have a problem.
 
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Old 11-16-12, 09:41 AM
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Sorry, didn't realize you are the 'sensitive' type.

My comment in post number 7 was intended to convey the fact that nobody here is OBLIGED to answer anyone. We're all volunteers and are all free to pick and choose who and when, and yes, even IF we answer.

this thread will be buried & forgotten long before my next trip
Only if you are the one who forgets about it. You are free to re-open your posts at any time you see fit.

Those options aren't available there. Besides the fact that they alert you to a problem that's already happened and prevents nothing.
Why not? No telephone line?

If you use the remote temperature alarm you can set it up so that it does alert you in time to at least TRY to make arrangements to have the situation rectified before damage is done.

But whatever... you said yourself that you aren't there and we're done.

Oh... before I forget... You're welcome. Wait... never mind, you didn't say Thank You.

Good Luck!
 

Last edited by NJT; 11-16-12 at 02:30 PM.
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