Problem with new thermostat (Maybe?)

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Old 10-17-11, 07:37 AM
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Question Problem with new thermostat (Maybe?)

I recently converted my steam heating system from oil to natural gas, so brand new boiler plus they also put in a new thermostat.

Lets say I have the thermostat set to 68 degrees during the day. The house will heat up to 68 just fine, but right now the temperature outside is just enough to keep the house at 68 without any further heating. However, the thermostat continues to kick the boiler on but only for a minute or two. No where near long enough to produce any steam.

I could see this making sense in a forced hot air system, where you get hot air blowing almost immediately so turning it on for a minute or two to maintain the temperature at 68 and keep a more steady temperature in the house.

However with steam ... you get no heat until the water starts boiling and the steam makes its way to the radiators.

Is it suppose to do this? Is it doing this so the water in the boiler never gets "cold" and thus takes less time to boil when heat is actually needed? Or is it just wasting gas?

In the old oil system it would also turn on periodically for a few minutes, not quite enough to make steam, then shut off. It would only do that a few times a day though (3 maybe 4? really don't remember). It would do this regardless of if the thermostat was set to "heat" or "off", I would flip the emergency off switch to keep it off. It seems to happen a lot more often now with the gas system though, but only if the switch is in the "heat" position.
 
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Old 10-17-11, 04:40 PM
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What thermostat is it? the cycles per hour may need changed...
 
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Old 10-17-11, 04:44 PM
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[the old oil system] It would do this regardless of if the thermostat was set to "heat" or "off"
What is the source of your domestic hot water in the home?
 

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Old 10-17-11, 05:06 PM
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Originally Posted by hvactechfw View Post
What thermostat is it? the cycles per hour may need changed...
Honeywell Pro TH4110D. I don't see anything in the manual about cycles per hour.

The hot water heater is electric, so independent of the steam boiler. We weren't going to do an indirect until the electric one dies.
 
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Old 10-17-11, 05:15 PM
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I can only guess, so here goes...

Your old boiler may have been set up for a 'tankless coil', even though one was not used. This would have been an additional control on the boiler that was causing it to 'keep warm'.

[the new boiler] more often now with the gas system though, but only if the switch is in the "heat" position.
This doesn't suggest a 'warm start' setup though, because if so, it would act the same as the old boiler... fire to stay warm whether or not the thermostat was on heat or off...

What is the new boiler make/model, and what controls are fitted on it? There should be a 'pressuretrol', that's pretty much standard on a steamer... but are there any other temp controls fitted?
 
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Old 10-17-11, 05:29 PM
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I don't see anything in the manual about cycles per hour
Page 8, setup function 5

http://customer.honeywell.com/techli...it/69-1849.pdf
 
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Old 10-17-11, 06:06 PM
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Originally Posted by NJ Trooper View Post
Well that would help explain it, I only have the operating manual and not the installer manual.

Function 5 was still at the default value of "5", but I'm guessing that should be "1"?
 
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Old 10-17-11, 06:14 PM
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Originally Posted by NJ Trooper View Post

What is the new boiler make/model, and what controls are fitted on it? There should be a 'pressuretrol', that's pretty much standard on a steamer... but are there any other temp controls fitted?
It is a Burnham Natural Draft Electronic Ignition, PIN5SNI-ME2.

I'm afraid I'm pretty unfamiliar with all the parts. It has the pressure control (I believe that's the pressuretrol you mentioned) that shuts it off when it reaches a certain pressure (I think it's set at 1.5 psi). There is an automatic water fill, and there is something on the flue that open/closes it automatically. I don't see anything else 'electronic' on the outside of it, other than the transformer.
 
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Old 10-17-11, 07:43 PM
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yes, I would set the CPH for 1
 
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Old 10-24-11, 01:46 PM
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Thanks everyone for your help, I really do appreciate it.

I've set the CPH to 1 as suggested, however it still is turning on periodically.

I'm not sure what's causing it, or if that's normal. It's kind of annoying to hear the radiators start whistling, but then it shut off before they actually start to get hot. This only seems to happen when the set temperature is equal to the actual. I'm wondering if it is some attempt to maintain the temperature? I'd rather the temp swings +/- 1 degree than only partially producing steam, seems like a waste of gas.
 
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Old 10-24-11, 05:01 PM
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Yeah it probably is a waste of some gas...

It would be nice if the thermostat had some kind of 'swing', 'differential', 'hysteresis' adjustment on it... look through the manual some more, see if there's any setting for 'short cycle control' ... or 'differential'...
 
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Old 10-28-11, 05:30 PM
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Only other thing really that I can see is "Adaptive Intelligent Recovery" which is suppose to just turn the heat on early to reach the set temperature at the set time, instead of turning the heat on at the set time.

It shouldn't be causing it to turn on any other time than the morning. I could try turning it off though, see what happens.
 
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Old 10-28-11, 06:07 PM
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Yeah, I've got a similar t'stat with that feature also... I think you are correct that it won't make any difference in the behavior.

they also put in a new thermostat.
OK, they might have not done something they should have done, and I wouldn't be at all surprised.

Where the wire comes out of the wall behind the thermostat, did they caulk or otherwise seal up the space around the wire? If not, you can have cool drafts from the wall cavity entering the thermostat body and messing with it's brainiac... hopefully it's on an INTERIOR wall too... but check that and see, it's a likely suspect.
 
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