Saveing MONEY ?

Larry_10

I don't set my t-stat back at night because I don't see it saving money.

Just add up how long your boiler runs in the morning to bring up to day temp it's about the same if you where to keep it in day temp all night. right?

for example if I keep my house at 69 during the day
and set my t-stat back to 65 at night

the burner will not run for 2 hours
then it will only run to keep your house at 65

but then in the morning count how long it will need to run to bring the house back up to 68. sounds like the same to me. I keep it at 68 all day and night so when I get up at night im not cold and it cost the same in my mind am I right?

help me understand this the only Benefit I see is some people like it cold at night but as far as saving money I don't see it

thanks

PS

Setback

Setting back does save you money - although a 4 degree SB probably won't save you much. There are conditions under which you will not benefit from setback, such as some high-mass radiant systems and structures with very high or low thermal mass, but otherwise it is well documented that savings can be had.

The warmup period (extra cost) after the setback will be equivalent to the cooldown period (extra savings). The savings derive from maintaining the lower temperature during the setback period.

Mike T., Swampeast MO

The Way I See It

"the burner will not run for 2 hours then it will only run to keep your house at 65"

As long as the burner has run for some period to MAINTAIN that lowered temperature you'll save some energy. If the burner never fires at the reduced temp you haven't saved energy--it just a larger than normal "bounce".

Larry_10

take a look at this calculator it says with a 4deg set back I will only save $8 a year not even worth getting up to a cold house at night this is with gas I have oil
dose this sound right I have a 1344 sqft house with r38 in the attic r19 2x6 walls and double pain Anderson windows

running a buderus boiler with baseboard heat

dose this sound right
http://www.alliantenergy.com/stellent/groups/public/documents/pub/bus_exp_eff_calc_010792.hcsp#TopOfPage

John Cockerill

set back

The only comfortable way to save money is to get control of the output of the boiler so you get just what you need from hour to hour. For hot water systems that would mean adjusting the boiler temperature range upward and downward as day get cold or warm. Most day go through a 20 degree swing in heat loss, as they go from cooler at 4am to warmer at noon. You can take the gamble in the morning as to what you should set things at. You can also keep charts for different days then set for the day you had set that temp before. Precision however is a very tricky thing as you could be ten degrees off either way on any day. I prefer the thermostat analysis and reset capability available from the thermostat provided by "Exquisite Heat". But everyone knows what I like. Best of luck. Let me know how you do with this technique. The spring and fall are times to set your aquastat each week. Do not go below 140 when setting your aquastat. I would say you will probably not have to go above 190. Once you get into your seasonal zone you should not adjust the aquastat more than 5 degrees each day, unless you get an unusual weather front in. Then ten degrees should do it. You will know whwn you have not got enough temp at the aquastat when the thermostat is not making temperature. You should surely raise the aquastat 5 degrees. and check thermostat setting against temperature at the thermostat 8 hours later. You'll get the hang of it. Keep charts and you can runa smooth efficient system and save 15 % on your fuel bill.

Larry_10

hi john yes I just bought a new controller for my buderus g115 I am taking out the 2109 and putting in the buderus 2107 with outdoor reset.

next year when I move to all baseboard and panel rads I will use the indoor room sensor to communicate with it

right now I use half baseboard and half hydro air. im just keeping the ductwork and air handler for cooling

thanks

PS

Unfortunately, setback analysis is much more complex than what results from that calculator - and I believe your home demonstrates my point. You will get the same values for a home with no insulation on top of a mountain

Heat load (conductive, infiltration losses), design temperature, delta, energy type and distribution system, local climate, etc - all factor in. I will try to find you a good link to explain it in greater (and clearer) detail. Hope I am winning you over!

Brent_2

setback

You save money because the btu's it takes to maintain the house at 65° is less then the btu's needed at 69°. You can run the numbers for your situation. You might fine it takes 120,000 to maintain 69 and 112,000 btu to maintain 65° at a certain temperature. (I'm just picking numbers out of the air) So each hour at that temperature you save 8,000 btu. Take those btu's times 6 hours a night times however many nights and you get some savings. Not a huge amount but some. As you said the heater runs more to bring the house up to temperature but remember during the time the temperature drifts from 69 to 65 the heater doesn't run at all.
I tell people to adjust the temperature to what they like for sleeping.

brent

PS

Reset

Be aware that OA reset is not the holy grail. In fact, a typical T-stat controlled system already takes into account the outside air - albeit indirectly. The colder it is outside - the more heat loss occurs. This is reflected in the number of heat calls generated by the T-stat. While OA reset is almost mandatory with condensing boilers, savings from controlling your delta can be had from any boiler.

Greg_15

From my own experience

Hi All:

I put a 7 day electronic tstat in 3 years ago. I had each day different for the occupied and unoccupied times. With a 10 degree setback for the unoccupied times I saved approximatly 120 gallons of oil per year. This paid for the tstat easily the first year. Fore the second year I left the temp the same through out with no setback. Both heating seasons were just about the same. I used just as much oil as I had befor I put the new electronic tstat in.

Setback works, my house is older, 2 story, with 2300 square foot living space. In 1998 I put a new oil furnace in and it cut my oil bil by slightly more than 1/3. I have lived here 14 years and always kept track of the heating bill, so I know it does indeed work.

Just FYI,

greg

Rich W

setback

Do you use Manual J for heat calcs.? The greater the Temp.diff. between indoor and outdoor- the greater the btu loss per hour (or gain for cooling). The more and longer you set back, the more you save.With an EMR thermostat we don't have to worry about how long it takes to recover from set back.

jerry scharf_2

Think like heat

Roosteboy,

I've learned a great deal about explaining things from the fine people on the site, especially Dan. I'm to the point like many others here where I see the heat flowing in my mind. Heat always flows from hot to cold. The rate at which it flows is based just a couple things, the temperature difference and the ways that the heat can move. There's a whole lot of subtlety on the how it can move part.

So setback directly operates on the temperature difference part. If you have less "push" the amount of heat that flows decreases. The only time setback would not save energy is in the case where the setback time is short and the control system overshoots on recovery to the point that the averaged temperature is higher.

Now there's a tradeoff between the overall way the controls work, the amount of setback and comfort. When you add outdoor reset, you are attempting to adjust the emitter output to the demand, and recovery becomes slower. This in turn decreases the comfort in the morning.

I've seen a very wide range of claims for the saving. My gut deel is that with hydronic heat in a well insulated house, the savings will be on the low side. With forced air heat, poorly sealed and insulated heating ducts, and a poorly insulated house, the savings will probably be dramatic.

With any of these eergy saving strategies, each change reduces the cost effectiveness of all the other changes. So doing a great job on insulating the house resuces the payback on the setback. Adding a high efficiency boiler then reduces the rate of payback for both the boiler and the insulation...

For many people, it's not a purely financial decision. I certainly will never recover the investment in the heating system of my house from energy payments. There are other issues and values to doing it that made the choice. In fact, I will posit that most decisions are made more at an emotional level than a financial one. Most people go with the lowest bidder on the heating system not because it's cheaper, but because they really want to be spending nothing and less is closer to their emotional goal.

jerry