I went to a gun fight with a knife, help?

Weezbo

One option would be to add some zoning. When you add zoning you could offer to zone certain areas of the home with much deeper setbacks and lower room temps....The potable Hot and cold water lines need to be considered in such a "scheme"...the idea there is without insulating anything ,without tightening the building envelope,without new emitters,without a boiler sized to prevent wanted btus zipping out an oversized boiler,without any outside help to clean the boiler or test the combustion, simply change the gert zone into many zones dial some of them( the ones in the areas least used) to much lower temps... dial the garage down to like 40 F here is how that scheme of things "Works"....the rooms that are used most often are the ones he wants to be comfortable at that time,other rooms or areas he could care less unless for some reason he happens to be in that room:) now by not "wasting heat to these spaces and dialing the zones down that heat is available to the areas he routinely inhabits. now if you put one extra emitter in the room he like to hang out in and That room responded more rapidly to meet his expectations the guy would be happy that it was saving money to operate the system and he finally felt comfortable in the...living room,den,office...dining room...bathroom :) where ever he happened to like hanging out :)

that is an option buh you would likely need a few more T stats and some more heat emitters in his favorite rooms,check the boiler combustion process check the Output of that boiler.locate the combustion air in the boiler room, and point out any minor technicalities you happen to see while there....

Another option would be to tell the guy to have a blower door test done on his home. Tell him its all psychological ... oops sorry ...did i say that :)

seriously the place might be large and zoning helps as does the other things that i have mentioned. my mantra though is insulate insulate insulate.....ventilate and heatilate and not too late. have a Habby day. consider the guys comfort physically and financially and you will have done yourself and him a favor. i would put one set back T stat in the living room and maybe the dining room.the garage i would dial down on its own zone to 10 to 20 degrees lower than the coolest room,and let the home owner dial the Mb and bath up or down as they see fit,the other 3 bedrooms would have their own zone and its pretty much set and forget... a great room i would put on a set back also....right now i am into set point controllers so its a little different..t stats are little bit less likely to preform quite the same....

when you are living in a cold room you are thinking 'Dammbitscoldinhere' and most people think'igottadosomethingaboutthisRightNow!' :)

so, 'Wheres the thermostat?' is usually the next thought. what if you went out there and the room he was liking to hang out in was far from a t stat? all kinds of glass? no emitters at all? can you see the value say of zoning? its 95 in the bed room:) the bathroom is 102 in the shade the dining rooms freezing the rest of the home ****:)) sorry...i digress...anyway, you cant ask what value set back will have if there is no way to get where he "lives" warm enough to suit his liking. who cares what the delta t is its Fricking Freezing in here :)))) sorry...er ...ehemmm...nah ... i have a sneaking suspicion that there is far more going on than the need of a set back t stat.

Lou Miller

Setbacks

There's a debate going on over at one of the woodworking forums. Now, I have some knowledge of systems, but I'm not even close to you guys. The debate is over whether or not you save anything by setting the thermostat back (5 degrees for roughly 8 hours), with a hot water baseboard system during the day when nobody is home.

I've talked to a lot of people over the years about this (that includes several of you here) and never seem to get the same answer. I know I've read some of you state that you get no benefit from a setback. I just wanted to hear the thoughts on this.

The situation is this: A house in upstate New York. The HO claims that he's spending $800/month for oil. In order to save money he wants to set his Tstat back 5 degrees when he goes to work and then raise it when he comes home. It's a single zoned system with one Tstat. Oil fired Boiler with cast iron radiators. I know it's hard to say for sure without seeing a house and knowing it's heat loss and so forth, but anyone care to give a generic answer? He's got to have some serious heat loss if he's spending $800/month. I don't know how big the house is, but since it's only got one zone, I'd tend to think it's not some monster of a house in terms of SF.

Weezbo

Dive and roll. come up cutting....*~/:)

to me it sounds like an oversized boiler with insufficent emmitters for the heat loss.no T stat is going to solve that.

soot_seeker_2

You know...

If they set it back at night, they would save far more than setting back during the day. In most parts it is about 5 - 15 degrees cooler at night.

As the house gets tighter and the mass gets higher, the potential for savings drop.

RonSBC

In every heat transfer calculation the differential temperature is used as a factor to determine the quantity of heat loss. as that number is reduced the factor then becomes less affective on quantity of BTU's work the equipment must then do. So yes he will save by setting back will it make him happy i doubt it, a five degree set back from normal set point during the warmest part of the day hence an already low differential temperature is'nt going to yeild the results he's probably looking for.

Lou Miller

I guess I'm wrong then...

Just a few questions if nobody minds then. Isn't there a recovery issue to deal with when you let the temp in the house get too low? Meaning that the boiler is going to have to run a lot more in order to bring the temps back up? One of the discussions was about a comparison between a forced air system and a hot water system. My point was that the two are apples and oranges. Citing that the forced air system will recover far quicker because there's a fan forcing the heat to circulate rather than waiting for it to radiate from the baseboards. Isn't the recovery time for a forced air system faster than a baseboard hot water system? Wouldn't there be a difference in savings and using setbacks with a forced air system versus a hydronic system? Did I get this one right, or am I wrong here too?

How about surfaces in the home? Won't you get the ambient temperature high enough to satisfy the Tstat, but yet still have items in the rooms that are colder, creating an uncomfortable condition? This condition could last for several hours too? Am I wrong about that as well?

I know that when I used to set the Tstat back in my house (oil fired boiler with cast iron baseboards on 4 zones in my case), and then returned it to our normal temp upon coming home, the Tstat would eventually be satisfied (seemed to take a looong time though), but it always felt cold in the rooms to us after the rooms were brought back to our normal temps. I no longer set the Tstat back and there appears to be a noticeable difference in comfort. Is that comfort just perceived, or is it reality?

Come on guys, throw me a bone, I gotta be right about something here. Well, not really, but it would be nice

Weezbo

what is faster, a molecule of water or a molecule of air?

if a gas is in a space ,how much of the space does it fill?

if i dig a hole in the ground and throw in a drop of water how much space does it fill?

how fast is the drop of water moving?

how fast is the molecule of air moving?

add energy... where did it go?

physics if phunny that way.*~/:)

it warmed up today. it is 40 degree F. when it warmed up to 20 below i was walking around in my T shirt.40 above seems sweltering. 50 below seemed cold. that type of Truth is posed in the Jain Doctrine of Manysidedness. it is different than the Socratic method.

will smith_4

Maybe we could get the Mythbusters to do a study for us! Probably get a much more honest and straightfoward response than if the DOE or one of our manufacturers did it...

Bill Nye_2

$800 ?

This guy has a huge house or no windows or doors. 5 ° set back isn't going to mean anything unless he tightens the structure up.

I heat a 1450 sq ft ranch with more outside walls than most [many additions] I have only burned $750 since September 2005. I filled up Tuesday this week. My house is either 69 0r 70 °, always.

The looser the house is, the faster the temp. will drop while it is off. The more energy required to warm it back up. There is really no substitute for adequate insulation.

You have to do other stuff too , like open the shades to let sun in and close them at night to keep cold out.

Wayco Wayne_2

For hot water systems

it is better to reset the water temperature according to outside temperature. I regularly use the Tekmar 256 and/or 260 outdoor reset control for this application. Many controls have a setback setting that sets back the reset curve when a time clock sends the signal for set back. This is supposed to be much more effective than a thermostat setting back the air temperature on hot water systems. WW

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Brad White_30

Now, THAT

is an excellent idea! Mythbusters.... Of course, I have not had a TV in years, not about to start now..

As UniR, Weezbo and Ron stated above there are many factors that come into play. No two houses are alike. Too few radiators and it is a long road back. Very good envelope? Diminishing returns. (Although in that case the temperature does not drop as fast while the boiler rests so why worry?)

In my own house in/near Boston, (6,000 degree days, 6F design) I used data loggers to see what the BTU elves did at night when I was asleep.

When I started I was renovating hence under-radiated. As expected the temperature graph dropped faster the colder it was out and the climb was atrocious until I added radiation. After tightening up the house more (infiltration sealing) the drop slope became more shallow and the climb, without radiation, still needed work. When I added more radiation without dropping my supply water temperature, I came closer to what I want, a shallow down curve and more rapid up curve. Not quite like an EKG but my heart is happier.

kevin coppinger_4

I'm w/ Wayne....

I have a tekmar 260 in my house and I leave the t-stat set at 67F and leave it....I have about 2000 sq. ft and use 800 gal/yr. w/ hot water use....he has to tighten up the envelope...kpc

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Constantin

Hmmmm....

Nothing like getting into a dogfight... is this at Breaktime?

Anyway, setback will help reduce heat loss by reducing the ΔT between the inside and the outside of the home. The less ΔT, the lower the heat flux.

Now, will setting back the T-stat by 5°F make a big difference, particularly during the day when the house may overshoot setpoint due to insolation? That depends on the house, the insulation, etc. At the very least, it won't hurt trying, just be sure that all areas of the house stay toasty enough for water and other pipes.

Tracking the fuel usage benefit is another conundrum, unless you go out and measure a number of factors like insolation, air temp, wind speed, etc. so that you can generate a reasonably accurate predictor based on them. Not everyone has the stomach or time for a regression analysis even if Excel makes it easy.

In the end, it's probably more effective to set back the Tstat at night when the heating loads are tyically highest (no sun to help). An outdoor reset controller with the right boiler or piping strategy will probably also do a better job. But, a programmable T-stat is a cheap investment, and setting back the place by 10-15 degrees during the day ought to be un-noticable if the turn-on time happens far enough in advance that no-one is home when it's 50°F inside.

JackFre

As pointed out

there are all kinds of things going on here. At $800/mo he should be happy to fund a building/system analysis. To decide that the set-back is going to save him dough (and I believe it will as long as he doesn't go crazy by dropping the temp big time)is just a band aid to a whole building issue. When I bought my house I lived in it for a year, found out some of what was needed and re-did windows, siding, building wrap. Amazing difference! Re-insulated the attic. Again, big gain. New Buderus with my Rinnai's Saved some more. After all that, as I'm remodeling some parts I'm re-doing sheetrock so I can reinsulated. My point is that this guy, and all of us, needs to get a program together to attack his utility cost. In spite of what Herr Bush thinks (if he really does) conservation does work. The magic stat alone won't get it done. What woodworking forums?

Rookie_3

Lets say the T-stat is set at 70*, calls for heat at 68* and the boiler cycles 3 times to satisfy the T-stat at 70* again. The heat loss brings the temp. down 2 degrees every 20 mins. What is the difference if the T-stat is set at 65*,
calls at 63* and still cycles 3 times to satisfy the T-stat
back to 65* every 20 mins. Unless you were within the 2 degrees of the outdoor temp. what difference would it make? 3 cycles to recover the 2* at 65* or 70*. Just a thought
..........ROOKIE

Doug_7

Thermostat setbacks save energy

Thermostat setbacks save energy regardless of the type of house or the type of heating system. The heating plant is there simply to replace the building heat losses and maintain a constant living temperature as per the thermostat setting.

There are some minor radiation and wind effects, but building heat loss is primarily due to conduction. Conduction is proportional to the difference in temperature between the inside of the house and the outside.

If it is 70 degrees inside and 20 degrees outside there is a 50 degree temperature difference or driving force for heat loss. If you reset the thermostat to 65 degrees you reduce the driving force by 10% and reduce the heat loss by 10%.

If you reduce the thermostat setting by 5 degrees for 8 hours you will save 10% on your heating requirement for about 6-7 hours because of the time required for the house to cool down and heat back up.

As pointed out nightime setback is also a very effective energy saving strategy.

Tightening up the building envelope and adding insulation is always your best move, but setting back the thermostat will save some heating energy in either case.

Doug

Rookie_3

Doug, I see 10% savings on the initial 5* setback. To maintain 65* once there wouldn't you need the same BTU's to
bring the temp back up to set temp. reguardless of setting 65* or 70*? if you have a 2-3 degree drop before it calls does it take less BTU's to bring 2-3* back up to 65* than it does to bring 2-3* back up to 70*? I've seen people drop their settings during the day when at work and at night when in bed but I still can't see any savings beyond
the initial setback which is lost back when the setting is brought back up. I do set my own lower at night but only because I like it cooler when I sleep.......ROOKIE

hr

I agree

with Doug. Heat loss is a delta t game. Reducing the inside temperature lowers the loss to the cold side. The widwe the temperature difference the faster the heat flow or transfer.

Chapter 1 & 2 of Modern Hydronic Heating explains this is an easy to understand format:)

I could see that too deep of a setback could not allow the building to warm for wake up time, depending on the equipment and emitter sizing.

Of course keeping the loss through the structure to a minimun is the wisest course of action. Think I would put my $$ in upgrading the building envelop, windows, insulation, air gap sealing, etc before investing in a setback control.

Keeping the heat inside, regardless of the delta t you are comfortable living with, will provide you best bang for the bucks.

hot rod

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Doug_7

Setback Saves

This is about house heat losses. Don't worry about the heating system. It will cycle ON and OFF as required to do its thing - which is to maintain the house at a constant temperature as per the thermostat setting.

Think about this: If in the example, you reduce the house temperature from 70 degrees to 65 degrees, the house will now lose heat at a 5% lower rate and will require 5% less Btu's from the heating system to maintain a constant house temperature. This 5% savings continues as long as the thermostat is left setback.

After that it is only about how many hours you can leave the thermostat set-back to achieve the energy savings. When the thermostat is returned to 70 degrees the house goes back to losing heat at the original rate. A few hours per day adds up to a big savings over a year.

If you reduce the house temperature from 70 degrees to 60 degrees, the house will lose heat at a 10% lower rate and require 10% less Btu's from the heating system to maintain a constant temperature. Do this setback (or more) if you go on vacation.

It may help to think about the extreme case. If you reduce the house temperature from 70 degrees to 20 degrees, the house will not lose any heat at all and will require zero Btu's from the heating system to maintain a constant 20 degree temperature.

Reducing the thermostat setting does save energy and the savings is proportional to the amount of the setback and the length of time it is setback.

Doug

Rookie_3

I got it now. Couldn't get past what the difference would be picking the temp up from a normal t-stat drop no matter where it was set. It took the extreme example of 20 inside and 20 outside with no HEAT LOSS to have the rest make sense. Thanks for getting through the concrete block after all this time.............ROOKIE

Gordy

How much is saved??

While I will not disagree that set back will save you money. The question is how much, and is it worth the trade off for comfort. If you use a regular 5% setback regime that would transend to a 5% savings on fuel, at least that is the claim.

Looking back at last years gas use, I consumed 1500.00 Worth for the season, this includes my water heater/ gas grill. I use no setback. This would equate to a savings of 75.00 for the season less than that if I deduct the consumption of the other appliances.

That dollar amount is not worth the trade off for comfort in my book. I do not wish to come home to a clammy house after working outside all day.

When you setback while gone for say 10 hours, the mass of the house, and its contents drop in temp also.... Radiant or FA. So now when you come out of your set back, these items have to be warmed up also. While your T-stat may get satisfied comming out of setback the objects will still lag a bit until everything is equalized. Learning t-stats will start the system early so that the house is up to temp when you walk in the door. So actually you may not be setback for 10 hours.

With all this being said I live in a 2300 sq.ft. dwelling. Your 5% could be more or less than mine. Just a different way of looking at the savings in my book.

If you want to argue the fact that if everyone uses setback so we are less dependent on oil, then that arguement wins hands down. But I think we need to look at the envelope of our structures, and the efficency of our fuel burning appliances to. That in itself would save more money than setback in my opinion.

Gordy

jim lockard

the home depot

commerical said "I could save a 150.00 per year with a set back T-Stat" J.Lockard

Gordy

Ehmm

That is deffinetly gospel then. HD I stand corrected.
Thanks Jim for the enlightening info. :^0. I believe aol had a whole host of energy saving %'s for different appliance,and home do's.

Gordy

Aidan (UK)

Setback

There was a question about heating a church (very high thermal mass) on another forum, here;

http://www.eng-tips.com/viewthread.cfm?qid=144273&page=3

This was posted in reply;


Here is something to think about, from CIBSE in the UK:

"THERMAL MASS AND CONTROLS
One technique often used to save fuel is intermittent
heating. This allows the building to cool down overnight
or when not occupied. The resulting lower average
temperature difference between inside and outside means
that, in theory, less fuel is needed.
This approach can create problems for masonry buildings
with high thermal mass, particularly if they are also damp.
As the building begins to warm up, surfaces, particularly
those most rapidly heated when the heating comes on,
begin to evaporate moisture at a high rate, raising the
dewpoint of the air. This may possibly even lead to
condensation on the cold structure at points which the
heat reaches more slowly. For example, in intermittently
heated churches with warm air systems, the floors
sometimes become damp shortly after the heating starts.
As this process is repeated, the effect is to distil moisture
from the warmer to the colder parts of the building. This
is most likely to affect windows, roofspaces, ‘cold bridges’,
window reveals, the corners of rooms, behind cupboards
and places where insulation stops. Mould growth - and
worse - can then ensue; and even glass can be affected
(see case study 18).
The second problem with intermittent heating is that, to
offset the ‘cold radiation’ from the unheated masonry
structure, the air has to be hotter than normal to provide
the same degree of comfort. The rapid changes in air
temperature and humidity can also cause damage to
decorated surfaces. There can be major problems where
salts are present, as these can re-crystallise as conditions
fluctuate. This can lead to accelerated deterioration of the
fabric and the rapid loss of historically and aesthetically
important surfaces such as stone carvings and wall
paintings.
Buildings with high thermal mass are generally better
heated continuously to a low level, or with night set back.
This can sometimes also prove more economical.
Occasionally, the use of a building is so low that full
heating cannot be justified. Here, one might consider
increasing the thermal comfort locally, for instance with
underfloor heating in the pew areas of a church. However,
in many buildings, a low level of background heating is
often justifiable as a form of preventive conservation, to
help keep the fabric dry and reduce the rate of
deterioration."

The thermostat only reacts to air temperature but doesn't take into account the radiant temperatures of the walls, floor & ceilings.

High mass buildings, like churches, are the exception that proves the rule. For those of us who don't live in masonry churches, setback will save a pile of cash. Is there any point to maintaining a space at a comfortable temperature when it's not occupied?

Outdoor reset and optimum stop/start will save a bigger pile of cash, whilst ensuring the space is kept at a comfortable temperature for the minimum fuel consumption.

Gordy

Weez

All good advice! As you said though "if you can't get to where he lives", how do ya know! I will bet the oil service is talking him into a bigger tank....less stops. 800.00 a month his house has to be huge, or he has screens for windows!

Gordy

Aidan

Interesting info. Wondering about the condensation issue, in smaller non masonary dwellings. Same principal applies, may be occuring where you can not see it.

Gordy

Aidan (UK)

Condensation

I doubt it, but I've no evidence either way.

They're talking about old stone or brick churches with stone floors in contact with the earth. I can't imagine you'd get that effect in a house, where all the surfaces would absorb less heat for a given temperature rise.

Greg_34

Basement or Underground Tank??

Please clarify if this tank is above ground in the basement or below ground outside.

I think you know where I'm going with this...

Dennis

Big old drafty houses

I had an uncle who owned a historical home built 1742. George Washington slept there, he froze too, but that was comfort back then.
Now my uncle found the best method of saving energy in very cold weather, turn the thermostat to 55 degrees, and go to Atlantic City to a hotel to stay warm.

This home has sold 3 times since my uncle vacated this home and the earth. The new owners have all spent 10's of thousands updating it, trying to bring some efficeincy to the place, all to move on.
I don't think it's financially possible to think these old homes can be made affordable to heat.

I would pray for a clenzing fire, probably the only time when the house will be warm, with little or no fuel usage.

Weezbo

I'm in Bermuda today.

was a hek of a run.worked the last couple days got on the aeroplane,finally arrived rented place got a toothache and basically havent had any sleep for the last 4 days *~/:) may touch in later when i get some asprin....

Doug_7

Right on all counts . . .

Lou - I agree you are right on all counts.

Yes - there is a recovery time issue. It will take some time for a house to fully recover from a thermostat setback. Length of recovery time depends on the thermal mass of the system and is different for every house. Higher mass system like PEX in Gypcrete will be much slower to cool down and much slower to heat up. Forced air is lower mass - quicker to cool down and quicker to heat up.

For the room to become comfortable again, the room air AND the room surfaces have to fully recover. Your body senses the higher radiant heat losses to cooller than normal room surfaces - and it "feels cool" even thought the air is back up to the normal temperature. The time for full recovery needs to be gauged and allowed for - deducted from the setback time. This is why automatic set-back thermostats are the best bet - so you can set the recovery time to start sufficiently BEFORE you expect to come home, so the house will be comfortable when you arrive.

Yes the heating system will run harder recovering from a set-back but you will save more energy during the cool down and while running at the lower set-back temperature than you will use heating back up.

With my higher thermal mass PEX in Gypcrete system I find short-term daily setbacks (when away a few hours) are not much use - the system barely gets cooled down before it has to heat back up. With a lower thermal mass system like hot air, staple-up or rads, there should be a very good energy saving advantage to daily set-backs when away.

With my higher thermal mass PEX in Gypcrete system, longer-term vacation setbacks are very advantageous. I typically set-back to 50 degrees F which saves about 40% on my heating bill. I have the thermostat come out of setback one day before I come home.

So thermostat set-back saves energy, but you have to know when to use it. You cannot generalize - every house is different. Works great on forced air, but for hydronic it all depends on the thermal mass of the system. Automatic set-back theremostats are a low-cost way to save energy and avoid the comfort issues.

Saving 5% may not seem like a big deal - but all those percentage points add up. You can save a lot more than 5% by improving the building envelope and the heating system efficiency - but this will also cost 10's of thousands of dollars. Set-back thermostats, by comparison, are a pretty cheap energy saving investment.

By the way - 5% of the U.S. crude oil consumption is over 1 million barrels per day.

So I agree you are right on all counts.

Doug_7

Lou - I agree you are right on all counts

Reply to earlier message from Lou -

Lou - I agree you are right on all counts.

Yes - there is a recovery time issue. It will take some time for a house to fully recover from a thermostat setback. Length of recovery time depends on the thermal mass of the system and is different for every house. Higher mass system like PEX in Gypcrete will be much slower to cool down and much slower to heat up. Forced air is lower mass - quicker to cool down and quicker to heat up.

For the room to become comfortable again, the room air AND the room surfaces have to fully recover. Your body senses the higher radiant heat losses to cooler than normal room surfaces - and it "feels cool" even thought the air is back up to the normal temperature. The time for full recovery needs to be gauged and allowed for - deducted from the setback time. This is why automatic set-back thermostats are the best bet - so you can set the recovery time to start sufficiently BEFORE you expect to come home, so the house will be comfortable when you arrive.

Yes the heating system will run harder recovering from a set-back but you will save more energy during the cool down and while running at the lower set-back temperature than you will use heating back up.

With my higher thermal mass PEX in Gypcrete system I find short-term daily setbacks (when away a few hours) are not much use - the system barely gets cooled down before it has to heat back up. With a lower thermal mass system like hot air, staple-up or rads, there should be a very good energy saving advantage to daily set-backs when away.

With my higher thermal mass PEX in Gypcrete system, longer-term vacation setbacks are very advantageous. I typically set-back to 50 degrees F which saves about 40% on my heating bill. I have the thermostat come out of setback one day before I come home.

So thermostat set-back saves energy, but you have to know when to use it. You cannot generalize - every house is different. Works great on forced air, but for hydronic it all depends on the thermal mass of the system. Automatic set-back theremostats are a low-cost way to save energy and avoid the comfort issues.

Saving 5% may not seem like a big deal - but all those percentage points add up. You can save a lot more than 5% by improving the building envelope and the heating system efficiency - but this will also cost 10's of thousands of dollars. Set-back thermostats, by comparison, are a pretty cheap energy saving investment.

By the way - 5% of the U.S. crude oil consumption is over 1 million barrels per day. That isa cost of $22 billion per year.

So Lou - I agree you are right on all counts.

Doug

Gordy

Beach Combing

You must be runnin around buck naked, combing the beach for shells. No wonder your tooth aches coming from -40* to 85*. Thats like a reverse ice cream headache. Enjoy !! you deserve it. Stay away from the JAVA!

Gordy