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Hot water heat, Set back thermostat? (11 Posts)
set back temperature at night?I have just moved into a new (to me) home that has and American standard hot water boiler heat system (gravity) It does a great job. The floor space is about 1100 square feet. The boiler is 100,000 BTU, I have six radiators creating the heat. I want to know if it is more economical to set back the thermostat to 60 - 63 degrees at night, or do I just cause it to work all the more in the morning when I set it back up to 70 degrees. As you must be able to tell I'm a consumer rather than a heating professional. but I need any help I can get. My only experience with heat has been forced air.
Driving tacks with sledge hammers...Based on what you've stated, the boiler appears to be two times larger than necessary. If this is the case, I don't think a programmable thermostat is going to save that much money. The boiler is suffering from short cycle syndrome. You might want to have a professional look at the system for potential down sizing. That could save you 30% right off the top. A typical savings from a programmable thermostat assumes an extremely energy inefficient home (leaky). If in fact your home is a leaky one, your time and money are better spent tightening the home up and making yourself more comfortable and conserving more of your hard earned $. Programmable T-stats in my opinion, mask other problems. Anyone else care to chime in... ME
Programmable statMark gives good advice! "Seal up and save" is not just a catchy slogan from some ad agency. Upgrading windows, adding additional insulation, weatherstripping doors and so forth will all add up. If your system is oversized and short cycles, you'll need a pro to correct it, use the "Find a Contractor" service above. Programmable stats are proven energy savers, but they are just a part of the system. Your house is one big system, and if one component isn't right, it effects all the others. Look for "Energy Star" ratings on any windows, heating/cooling equipment, water heaters, thermostats etc. that you may be considering.
Oversized boilers and old gravity systems> Based on what you've stated, the boiler appears
> to be two times larger than necessary. If this is
> the case, I don't think a programmable thermostat
> is going to save that much money. The boiler is
> suffering from short cycle syndrome. You might
> want to have a professional look at the system
> for potential down sizing. That could save you
> 30% right off the top.
> A typical savings from
> a programmable thermostat assumes an extremely
> energy inefficient home (leaky). If in fact your
> home is a leaky one, your time and money are
> better spent tightening the home up and making
> yourself more comfortable and conserving more of
> your hard earned $.
> Programmable T-stats in my
> opinion, mask other problems.
> Anyone else care
> to chime in...
I would doubt the boiler is short cylcing even if it is oversized because there is so much mass in the system to absorb heat that it would still run the boiler on long cycles. However the time between the cycles would also be very long. I have used Honeywell high end thermostats very successfully with gravity type hot water systems when they had pumps added and the boiler was properly sized. The problem that tends to happen is overheating when the system comes out of setback. The way to avoid this is to use a higher grade thermostat and then have it come out of setback early and to a temperature a few dgrees cooler than the comfort setting. Then have the thermostat set up an hour of so later to the comfort setting. This allows the system to coast up to the temperature the last hour or so, helping prevent overheating.
Oversized boilers and old gravity systemsI would doubt the boiler is short cylcing even if it is oversized because there is so much mass in the system to absorb heat that it would still run the boiler on long cycles. However the time between the cycles would also be very long. I have used Honeywell high end thermostats very successfully with gravity type hot water systems when they had pumps added and the boiler was properly sized. The problem that tends to happen is overheating when the system comes out of setback. The way to avoid this is to use a higher grade thermostat and then have it come out of setback early and to a temperature a few dgrees cooler than the comfort setting. Then have the thermostat set up an hour of so later to the comfort setting. This allows the system to coast up to the temperature the last hour or so, helping prevent overheating. If looking to save energy with the smallest investment, start by air tightening. Weatherstrip window and doors, seal air leaks on the inside of walls around trim, outlets, switches, light fixtures and other penetrations on exterior walls and ceilings. Do not seal up lighting that requires ventilation! Start at the top of you home and work you way down. Then after tightening things up insulate The exterior ceilings, then walls(if possible), and after that install storm windows. This is usually the order of most cost effective to least cost effective ways to improve your home to reduce energy costs. With these improvements heating energy usage can be cut in half when starting with an older leaky, uninsulated home. I've done this with my 2800 two story 1906 home with over 700sq ft of windows. Here in Norhtern Illinois my yearly gas cost for heating comes out to about $350.00 per year using and oversized 1962 American Standard boiler (probably about the best cast iron boielr ever built) With the recent increases in gas cost this might now be closer to $500.00. Boilerpro
Boilerpro, how much do you pay per therm for natural gas? I wish it was that inexpensive to heat in NY. Did you retrofit the American-Standard with a vent damper and new gas train, or is it all original?
Some up grades and ....We were paying about 33cents per therm midwinter. It's been that price since the late 70's. Everybody's up in arms because it has jumped to about 60 cents per therm. I keep telling them that we are still below the national average. Upgrades to the boiler include a good fireside cleaning, thermally actuated damper, cleaning the old cast iron ribbon? burners, and removing 6 of the 9 burners and plugging the orifices,cutting the size of the flue pipe, and installing a Hofmman 21 H mixing valve on the return to keep the boiler at proper temp. Wouldn't do most of this on anyone else's boiler..... too much liability. Still using the setback thermostat on the main zone (about 3/5 's of the home) with the rest being kept about 55F. Off to WEtstock - Chicago! Boilerpro
Let me add to my situation please.I was initally asking if there was energy savings by setting back the thermostat at night to 60 degrees. What I am hearing is that the boiler is oversized. This presents me with another question. This is an older (1910) two family, two and 1/2 story bldg. (third floor has no radiator at the moment, although there are pipes for a radiator, which I would like to add to) We have had installed two central air units, the third floor also had installed a resistance electric heat furnace. We are tightening up the house for air leaks with insulation and replacement sash windows. The heating system consists of two boilers. First Floor American Standard gravity drain system 96000 BTU Output. The second floor uses a more modern Bryant 100000 boiler with a B&G recirculating pump. Each floor has approx 6 13 to 15 tube American radiators. One additional will be added for a large master bath and possible one on the third floor area. My question now is, can I tie the system together to use only one of the boilers and if so which? American Standard with the pump added. (It looks like its from the 40s or so, not sure) The Bryant was put in during the early 80's. I have started and met with a heating contractor, who of course is excited over the newer Weil-Mclain Ultra Boiler and would like to sell me that system (This is an expense I would like to avoid at the moment and add later) I'm trying to find either the best way to go. (cost of operation plus comfort) balanced with cost. The third floor is used only on occasion for Sewing. I would like to add a radiator there, simply because I don't want to pay the electric heat. The furnace IS there, if the radiator option doesn't work. I do understand that a "Heat Loss calculation is needed", just need a rule of thumb direction as to what to do. Again Thanks David
If you look at some ofthe other resent posts you will find that gravity systems take care of themselves and what you gain in setback is lost bring the home back up to tempurature even with the suggested double ramp up to daytime set point, Being a heat pump head before these guy got me all wet, I don't feel set backs gain a great deal in energy savings. If you got here you can get a heat loss calculator. Check out the pipe in the corner. Here in beautiful Sheffield Lake OH, on a house that you describe, especially along the lake shore, your load could require what you have. Remember a bunch of that input rating goes up the flue. I like the whole house as a big system phrase. Can I steal that or is copywrited? Are you changing the home from a two family to a one family? I would say you sure could add some radiation to the "attic/sewing room", especially if the pipes are there. You may need to fuss with the opperating pressure to fill the top radiator. I wonder why we go up to the third floor to sew, happens around here alot. Where are your expansion tanks? Why the pump on the newer system? Do you think it got added because it shipped with the equipment? The boss caught me goofing off, back to writing the spring news letter. Good luck, Mark To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
Yes this is a conversion to a single family. Sewing area on third floor because it has the space and it can be left all set up and heat shut off when not in use. You said I might need the load I have, does that mean I need the whole 200,000? or 100,000? The Input BTU is 125,000 which I assumed was the loss including up the flue. As to the pump on the second unit, I don't know. May have been added when the boiler was changed out. I thought perhaps it was because over the 90+ years the pipes may have corroded causing more resistance. (purely guessing) I appreciate the input from everyone. thanks
gravity systemBoilerpro's got it working. I have a customer with a mish-mash similar to this. IMO do not set-back. These old gravity systems work fine maintaining the temperature you are looking for. They take too much energy going out the stack to bring your comfort level up. I believe they were made for coal. My customer(oil)has an approx 117k oil converted gravity boiler w/a warm air furnace, and a loop off an oil-fired water heater for the new breakfast nook zone. I try every chance I get to consolidate and after this years' oil prices, and me shouting effficiency and conservation, I believe this is the year.Going to do a whole house heat loss and attempt to sell staple up radiant, towel warmers in the too cold bathrooms upstairs, all kinds of goodies. I know I can save them 25-50%, and make them more comfortable in this circa 1910 old-time mansion.