New to boiler hot water heating system

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Old 01-08-14, 07:32 AM
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New to boiler hot water heating system

We just bought a home with a natural gas boiler hot water heating system (new boiler installed in 2009). Home inspector claims it's one of the more efficient kind of heating systems (we've always has gas forced air).

My question is this: Assuming it takes quite a bit of time (and natural gas) to heat up the water to run throughout the whole system, is it more efficient to leave the thermostat at a set temp of 70 degrees, or utilize a programmable thermostat to drop setting to 66 or 67 when we are not at home daily, etc....?

We live in upstate New York, where December to March temps can go below zero often, and "normal" is in the teens-20's at night and 30's during the day....

Thanks so much!
 
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Old 01-08-14, 08:02 AM
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is it more efficient to leave the thermostat at a set temp of 70 degrees, or utilize a programmable thermostat to drop setting to 66 or 67 when we are not at home daily, etc....?

I set it and forget it... I seem to save more fuel that way... I do drop the t stat 2 degrees though when not home for long periods..

70/68....

What is the make and model of your boiler?

If a mod con boiler then its best to set it and forget in IMO... Especially if you have in floor radiant heat...


Oh and welcome to the forums....... [ATTACH=CONFIG]24451[/ATTACH]
 
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Old 01-08-14, 08:05 AM
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Assuming it takes quite a bit of time (and natural gas) to heat up the water to run throughout the whole system, is it more efficient to leave the thermostat at a set temp of 70 degrees, or utilize a programmable thermostat to drop setting to 66 or 67 when we are not at home daily, etc....?
All of the 'green' websites, even the D.O.E. and others will claim fantastic fuel savings by employing a setback thermometer.

I for one don't buy it.

Short time periods (say 8 hours) of 'steep' setbacks, in my opinion, don't save enough fuel to make them worthwhile. In fact, you may even end up using MORE energy...

It's not just the water in the system that cools down, it's the ENTIRE STRUCTURE, the furnishings, all of it.

So let's say we set back 5 during the day... are we really going to save enough energy to overcome the constant boiler running for a couple hours to warm everything back up to make it worth while? Not to mention the discomfort of living in a cold house during this time...

AND... if you have a high efficiency system (what model is it by the way?) it could take even LONGER to recover from a steep setback due to the way they are controlled.

I don't think any setback that takes more than 1 hour to recover from is good. This is probably about a 2 or 3 degree max setback.

By the way, my opinion is actually based on experimentation I did several years ago. I have a setup that allows me to calculate exactly how much oil I'm burning... an 'elapsed time' meter tied into the oil valve on my burner. I track the 'heating degree days' also. Knowing this data allows one to establish a mathematical 'constant' by dividing one into the other. Using this constant, I was unable to discern ANY fuel savings. There may have been SOME, but if there was, it was too small to 'see' in the data.

Your mileage may vary.
 
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Old 01-08-14, 09:39 AM
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It's not just the water in the system that cools down, it's the ENTIRE STRUCTURE, the furnishings, all of it.
Which of course means that the overall comfort level of the people inside the structure is also diminished.

Something else about nighttime setbacks that sometimes gets overlooked in the discussion: while the home is cooling down on the inside, the darkness is (usually) contributing to colder temperatures outside. Which is another reason for those uncomfortably-long morning recovery periods.
 
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Old 01-11-14, 05:13 AM
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Thanks for the info so far.... The boiler was installed 2009. It is a Peerless Boiler (Natural Gas). Model # MI-04-STDG-WPC. A few other stats are:

Max BTU Input/hr = 105,000
D.O.E. HTG Capacity = 86,000
Max Gas Supply Pressure in WC 13.5 (Min 5.0)
Ratings 75,000 BTU/hr water

From your responses so far, it appears it's best to just leave the thermostat at 70 degrees 24/7 .... other than vacation periods away from home.
 
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Old 01-11-14, 06:22 AM
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new to boiler

If the theory of heat, which is heat travels to cold and the greater the difference the faster the heat travels. If the temperature outside is the same as inside there is no movement of heat and no consumption of fuel . If you require the inside to be higher, than fuel has to be burnt to make this happen .In my opinion due to the theory of heat there must be a fuel saving when the inside temperature is lowered and the greater it is lowered the greater the savings . Comfort is another separate problem.
 
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Old 01-11-14, 07:34 AM
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In my opinion due to the theory of heat there must be a fuel saving when the inside temperature is lowered and the greater it is lowered the greater the savings
That's not an OPINION saves... it's a FACT.

And of course that is true as a general statement. AT STEADY STATE.

You will get no disareement from me on that fact.

HOWEVER, consider this... and keep an open mind, no hubris allowed...

Take a building that is comfortable at 70F. There will of course be a certain heat loss.

Same building, set back the t'stat to say 65F. The STEADY STATE heat loss will obviously be lower than at 70F.

Can you calculate the BTU decrease? Sure... run the heat loss software at two different temperatures for at least a rough estimate.

Next, can you calculate the EXTRA BTU required to bring the entire structure and all it's furnishings back up to temperature after a setback period? Very difficult to do without knowing the physical properties of every single different item in the building. If it were WATER, no problem, that's well defined... but building material? I don't think so Tim.

My opinion is that any savings gained during the setback period will be eaten up by the EXTRA BTU required to reheat the structure, it's furnishings, and all the air contained within.

If there's any savings to be gained, it is VERY SMALL. So small that in several years of real world data collection in my home I was not able to detect that savings from the 'noise' in the data.

AT BEST, I consider it a WASH.

it appears it's best to just leave the thermostat at 70 degrees 24/7 .... other than vacation periods away from home.
I would not argue over say a 2F or even maybe 3F setback if it gives one a 'cool fuzzy feeling' that they are doing something to save energy... as long as it only takes an hour or so to recover from that setback period.

Of course turn it down during vacation periods. As long as this doesn't cause cooler areas of the home to drop below freezing during periods between heating cycles and cause pipes to freeze and burst. Longer periods of setback absolutely WILL save energy.

I don't see any savings occurring on the relatively short 6-8 hour setback periods that people generally use.

NOTE: My data applies to hot water heating only... I've never done any testing with HOT AIR ... even though I'm full of it... and there is some evidence that because hot air seems to recover faster (but this may not be completely true... the AIR recovers faster, but the structure and furnishings are still cold and the furnace will still cycle more often as the heat in the air radiates into the building to reheat the structure... it may be a WASH also, but I have no data to support that possibility) there may be marginal savings.
 

Last edited by NJT; 01-12-14 at 08:20 AM.
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Old 01-11-14, 10:26 AM
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I am currently in the middle of this type of test in my own home. It will be done at the end of the month and I will then take my data and come to a conclusion on whether or not, set backs equal fuel savings. If anyone wants to see this data I should be done by the first week in February. I will post up a thread on this forum when it's completed.
 
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Old 01-11-14, 10:36 AM
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I would love to see it! Looking forward to hearing about it....
 
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Old 01-12-14, 04:59 AM
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Thank you all. I'll keep the thermostat at 70 and forget it.
 
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