# Ok to shut off Furnace?



## daveswoodhauler (Feb 4, 2011)

Maybe should have gone into the green room...not sure?
Ok, so we have an oil fired furnace and also a small tank above the furnace that is used for hot water. (Don't have a seperate hot water tank....basically a thingy that looks like a balloon above the furnace)
During the winter, we use the stove a lot, and other than showers in the morning and baths at night, we really don't use any hot water.
Any harm in shutting off the furnce during the day, and then tunring back on before we go to bed? 
Just tired of the furnace kicking on every hour or so while I am at home to heat the water we are not using...seems like a waste of oil...but I am sure someone has tried it here?


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## DWW68 (Feb 4, 2011)

will not hurt anything. it will just take longer for the water to heat to temp. in some cases it may take more fuel to bring water up to temp than it does to keep it at temp.


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## semipro (Feb 4, 2011)

If the "balloon" is not already insulated adding some would help a lot if you go this route.


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## szmaine (Feb 4, 2011)

Actually, we just had our dead boiler replaced and had alot of chats with our very nice installers.

We had run the old boiler that way for 4 yrs. You do indeed significantly reduce oil consumption needed to maintain temps on a warm start boiler which it sound like you have. Our installers said this is bad for this type of boiler as it degrades the gaskets among other things. I'm not saying it killed our boiler since a 50yr old boiler has gone far above the call of duty - just passing the message along. Got a cold start now, solves the problem.

PS - That balloon is the expansion tank I think. The water being heated is the water inside the boiler.


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## woodgeek (Feb 4, 2011)

That thing is probably an expansion tank--do you have hydronic heat, or forced air ducts.  If the former, your 'furnace' is a boiler.

If it is a boiler, some folks say that deep thermal cycles (such as shutting down daily) can increase the probability of their seals opening
up and leaking/failure of the boiler.  Modern boilers (often in stainless) are designed for deep cycling and shutdown, older ones in cast iron
not so much.  That said--I deep cycle mine whenever I go out of town, and I think the previous owner cycled it daily.


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## billb3 (Feb 4, 2011)

every hour or so seems a bit much

I think mine comes on 2 times a day in the Summer.

and the balloon thing may be the expansion tank. 
Mine is in the radiator line and would be hot when hot water is going to the radiators.

My furnace started leaking when I decided to shut it off last Summer when I went to Europe.
Once I got it going again and warm it stopped.
8 hours or so might be fine.


(I have to shut mine off at the circuit breaker. I don't know who wired the safety switch, but it doesn't do anything)


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## mayhem (Feb 7, 2011)

I shut off my boiler every day after we're done with the hot water.  Turn it on when I get out of bed, the hot water tank holds enough hot water that I can get a coule showers out of it, or a load in the dishwasher and a hot shower.  The darn thing cycles like 2-4 times per day every day, even in the summer just to keep the hot water hot for me...if I cna plan ahead 15-20 minutes and turn on the boiler that long before I want to jump in the shower I cna have a nice hot shower and not waste much oil.  I figure this probably saves me a quart or so of oil every day...though I don't actually know my consumption rate...its a pretty big boiler to use for hot water.


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## WES999 (Feb 11, 2011)

The" balloon thing" is likely not a expansion tank, it is probably a heat exchanger, it heats DHW with the boiler water. This is the type of system I have. It is probably the most inefficient way to make DHW. I switched to an electric tank water heater which is cheaper to run. It was costing about $90/mo in the summer to make DHW, an electric is about $25. And the water temp is much more consistent. 
More info here.
https://www.hearth.com/econtent/index.php/forums/viewthread/39434/P0/


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## daveswoodhauler (Feb 11, 2011)

I think WES is correct in that it is a heat exchanger...thanks to all the replies. (Also, thanks for the link WES)
I am coming up with the same numbers for hot water in the summer, between $80-$90 month to operate...according to my spreadsheets and looking during the summer, looks like I am using 1 to 1.2 gallons a day just for hot water. I am looking to go with an electric hot water tank, but I am a but leary as we have well water, and in speaking with my boiler tech a lot of folks in the area have had problems with the water being hard and gucking up the boiler parts. (We have had no issues though)
Gott research this some more....thanks for all the help folks.


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## homebrewz (Feb 11, 2011)

If its cast iron, won't there be issues with rust if the boiler is shut off for extended periods, perhaps several days? 

If you have hard water, draining the hot water tank once a year may help with accumulation of deposits. I seem to remember a discussion about this on here a few years ago. 

Something else I remember reading here or on a solar DIY website.. A quick and cheap solar project would be in the summer to pipe the DHW lines into an old water tank painted black, situated where it will get full sun, and then piped back into the system. Don't know how well it works, but sounds cheap and easy if you're good with plumbing.


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## daveswoodhauler (Feb 11, 2011)

I hear you Home Brew....my idea of shutting off the boiler during the day is just not the right approach....just hate the sound when it kicks on if you know what I mean.
I really need to consider either an Electric Tank or another route...perhaps Solar.
I'm in the process of building a family room in our basement, and since we are going to add a third zone for heat I'll check with the plumber to see the cost to have our system converted to just an electric unit. I don't mind the cycling during the day during the winter, as we do use the boiler for heat at night and real chilly days....just the $90 I am spending in the summer gets to me.
Looks like another project


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## homebrewz (Feb 11, 2011)

I do know what you mean.. don't like that sound either.

The furnace in the house I grew up in made DHW and after decades of service, the coil finally gave out due to being plugged up with deposits. I knew getting only 5 minutes of hot water in a shower wasn't right! My Mother had an electric hot water heater installed. So, now the furnace just heats the house and she goes through less oil and has pretty decent hot water. 

You might look into the return on investment for solar DHW. It doesn't seem to be that great if you pay for everything outright. If you DIY it, flat panel collectors are relatively inexpensive, or you can even make them your self. There are also other thermal masses to pipe water pipes through.. stone masses and the like. You'll also need to consider some form of storage. The possibilities are many.


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## WES999 (Feb 12, 2011)

I have a home made solar pre-heater for the summer, and a hot water coil in the basement wood stove for the winter.

I picked up my hot water heater for $50 on CL. Turns out it has a plastic liner so it should last a good long time.

I don't think the furnace has turned on more than 3 or 4 times this winter.

Last time I purchased oil was about a year and a half ago. :cheese: 

There is a write up on mu solar system here:

http://www.builditsolar.com/Projects/WaterHeating/Metal1K/Metal1K.htm


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## woodgeek (Feb 12, 2011)

I have a oil-boiler fired DHW system, and I too noticed it was running ~1.2 gals/day standby in the summer.  The odd thing I asked was where was the heat going? that is about 1.5 kW standby heating, and my boiler room was warm but not THAT warm.  I figured out that my system was thermosiphoning--all the radiators were a little warm due to gravity fed circulation.  I closed a ball valve in my main hydronic line (after the heating season was over) and my standby dropped to 0.5 gals/day.  Adjusting the aquastat, I got it down to 0.35.  Closing and opening the valve once per year saves me ~150 gal/yr in oil and is cheaper than a new system.


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## peakbagger (Feb 13, 2011)

Some cast iron boilers seem to have problems with leaking between the sections when they are cycled. I havent had any issues with mine but I have talked to several folks who have had issues, that went away when they went back to a hot standby. I havent had any issues and I used to only run mine when I needed hot water so it got turned on and off every few days. Dont worry about rust in cast iron boilers, unless you drain them they wont rust while sitting cold. With my solar hot water panels, it stays down from about late April to early October.


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## homebrewz (Feb 14, 2011)

We have a Peerless WBV-04 cast iron boiler, about 10 years old. This thread has me intrigued.. especially since it seems rusting is not an issue. With primarily wood heat, its just used for DHW and backup. Any thoughts on seals leaking during shutdown with this particular boiler? Also, am I correct in assuming I can just shut off the flow to the baseboard pipes during the summer? I'm a DIY'er, but know little about boilers and plumbing.


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## Don2222 (Feb 16, 2011)

Hello

It sounds like you have a tankless coil and an older boiler that is NOT a cold start boiler. Shutting it off every day will greatly decrease the life of the boiler and is not recommended by my boiler man. I was going to install controls that would automatically do that but instead got a new COLD start boiler and now I am all set!

I only use the new boiler for DHW and turned off the zone thermostats. Since the fill up of oil I got in sept I have only used Half a tank of oil!!


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