Shutting off your oil boiler?

[Martlet]

I currently only have an oil boiler for heat and hot water. My boiler kicks on throughout the day, even when I'm not using hot water. I just read an article that suggested flipping off the red shut off switch when you aren't going to be home or using hot water, then turning it on when you get up or get home.

Has anyone heard of this? Will it save you oil? Is it harmful to the boiler?

 

[velvetfoot]

What a pain. Buy a cheap electric water heater.

 

[sportbikerider78]

No. I had the same setup until I added an electric hot water heater. Best $300 I ever spent.

 

[Martlet]

No. I had the same setup until I added an electric hot water heater. Best $300 I ever spent.

Big savings over the oil? Why don't people do it to begin with, then? I had natural gas at the place I just sold.

 

[sportbikerider78]

Very much so. Oil is expensive when compared to electricity.
Electric water heaters are also 100% effecient because all heat goes to the water. With oil, a great deal of heat goes up the chimney.

They did it because oil was cheap when that system was installed.

Natural gas water heaters do make sense. They burn super clean and natural gas is cheaper than oil.

 

[heat seeker]

Heating and cooling a boiler repeatedly can cause it to leak at the seams. That idea cost my parents a furnace in less than a year. It's not meant to be treated like that. A separate water heater is a better idea. One house I owned had a separate oil fired water heater, so I shut the furnace off every summer for 26 years, no problems. But that was only once each year.

 

[Martlet]

This is why this forum, while confusing because of the incredible knowledge of some posters, is invaluable to me, the novice. This thread might have saved me a furnace.

 

[heat seeker]

I must amend my comment. The furnaces I refer to are the cast iron type. The newer ones that are made of sheet metal are actually meant to be heated and cooled repeatedly, in the interest of efficiency. The cast iron ones I knew leaked where the sections were joined, and the gasketing in between couldn't take all the expansion and contraction. I'm sure the furnaces could have been repaired, but it wasn't economically feasible.

I hope that I haven't fogged up the topic too much...

 

[billb3]

I currently only have an oil boiler for heat and hot water. My boiler kicks on throughout the day, even when I'm not using hot water. I just read an article that suggested flipping off the red shut off switch when you aren't going to be home or using hot water, then turning it on when you get up or get home.

Has anyone heard of this? Will it save you oil? Is it harmful to the boiler?

Some older cast iron boilers could leak . The new cast iron boilers are OK.
You might be able to adjust the aquastat settings to have the boiler stay warm rather than hot but this would be best determined by whomever services your boiler every year. How much would depend on the model boiler, if you have a tankless coil, or hot maker, etc . They Could do it for you or show you how.

If your electric rates are 27.5¢ Kwh there like they are here you won't save any money with a cheap water heater.

 

[Ashful]

No. I had the same setup until I added an electric hot water heater. Best $300 I ever spent.

So, you spent $300 on a product with an average predicted lifespan under ten years to save a few pennies per day? Most families use about 1 gallon per day of oil for off-season DHW production, with a very small fraction of that going to the standby losses being discussed here.

I'm not saying oil is the best system to install today, but spending money to replace a functional oil system is not going to have a favorable 5-year amortization, in most average cases. Let's not forget that electricity ain't exactly free, either.

Let the boiler run, you have bigger fish to fry.

 

[peakbagger]

It depends on the boiler, some leak when they are cycled from hot to cold, some don't. Older boilers tend to be more of a leaker but newer designs are less prone as "cold starting" is slowly being accepted as a way of operating. I have 25 year old crown oil boiler that I have cycled on and off for at least 15 years that doesn't leak. Prior to doing this I figured the boiler use about 1 gallon a day to stay warm for 6 months. I switched to solar hot water at one point and then I just left it off all summer.

Rarely is there long term damage from at least trying to cycle the boiler. If you cycle it and start to see leaks then don't do it. It is important to ensure that your expansion tank is in good shape and not flooded as cycling the boiler with a bad expansion tank is almost a guarantee that it will leak. The other thing to investigate is that you have an separate expansion tank on your hot water system.

 

[maple1]

So, you spent $300 on a product with an average predicted lifespan under ten years to save a few pennies per day? Most families use about 1 gallon per day of oil for off-season DHW production, with a very small fraction of that going to the standby losses being discussed here.

I'm not saying oil is the best system to install today, but spending money to replace a functional oil system is not going to have a favorable 5-year amortization, in most average cases. Let's not forget that electricity ain't exactly free, either.

Let the boiler run, you have bigger fish to fry.

I had estimated that when we had our oil boiler, we used about 0.8gal/day (Imperial) of oil for DHW in the summer. At our oil prices, that figures to about $125/mo.

Since getting rid of oil & when heating our DHW with an ordinary electric hot water heater, and after looking at the bills for the first summer of doing that, I estimated it cost in the area of $25-30/mo. to heat it that way (at $0.18/kwh).

So the difference was real dollars and not pennies - in our case it amounted to around $100/mo that we saved moving to an electric water heater. Then if you factor in the extra load the standy by losses add to your a/c load, if you do a/c - there are more savings there, although that one would be a hard one to put numbers to. But the cost of making the switch was easily recovered the first year, and the savings were $100/mo +/-, every year after that.

That's our experience. Not saying everyones will be the same - but everyone heating their DHW with a boiler in the summer months should take a serious realistic look at their numbers. I should have done that years ago.

(Things get even more interesting if you start looking at heat pump water heaters, which can also do some dehumidification and take even more load off the a/c while using even less electricity to heat your water.)

 

[moey]

What kind of boiler do you have?

Your boiler is maintaining temperature via the aquastat. I suspect the boiler is cycling when it cools to 140-150ish. If your boiler has a large thermal mass you wont save much by shutting it off youll save a little but you have to heat that thermal mass back up again to make hot water. You may create other problems old cast iron boilers dont like to be warm. They can be hot and in some cases cold for long periods but being warm usually is not good.

 

[sportbikerider78]

So, you spent $300 on a product with an average predicted lifespan under ten years to save a few pennies per day? Most families use about 1 gallon per day of oil for off-season DHW production, with a very small fraction of that going to the standby losses being discussed here.

I'm not saying oil is the best system to install today, but spending money to replace a functional oil system is not going to have a favorable 5-year amortization, in most average cases. Let's not forget that electricity ain't exactly free, either.

Let the boiler run, you have bigger fish to fry.

I estimated payback to be about 1.5 yrs...and I don't have a heat source in my basement for the warmer months.

 

[Ashful]

I estimated payback to be about 1.5 yrs...and I don't have a heat source in my basement for the warmer months.

Maybe a better argument, if you had installed a HPWH, in which heat extracted from the basement overwhelms its radiated losses. Unfortunately, your electric water heater is still a net heat loss into the basement, albeit a little less than the boiler.

So, maybe you're saving a little. At the same time, I hope I never need to worry about problems on the scale of $150/year. When the boiler dies, I'll evaluate the most cost-effective system to replace it at that time. Until then, I don't see any substantial benefit in worrying about it.

The only possible exception to this would be the aforementioned HPWH. If you use your basement for a rec room, exercise room, etc., then it might make sense to have some free summer-months cooling down there. In addition to gub'ment reimbursements, which can make them very inexpensive, you could also save $100 per month (not per year) on dehumidifier usage. There's real benefit, there.

 

[velvetfoot]

If, oil is at 2.80/gal, and you use .75 gal/day for dhw, that comes to ~$65/mo.
If the electric hw heater costs $25/mo, which could be high in my case, that comes to a savings of $45/mo.
If the electric hw heater cost $300, that would come out to a payback of 7 months.
Even if the numbers aren't all correct, it would seem to point to a short payback.

 

[Dougsey]

In addition to gub'ment reimbursements

Are there 2015 federal tax credits for HPWH?

 

[maple1]

...you could also save $100 per month (not per year) on dehumidifier usage. There's real benefit, there.

I saved $100/mo just from the switch from oil to electricity.

Real benefit, there.

 

[sportbikerider78]

Maybe a better argument, if you had installed a HPWH, in which heat extracted from the basement overwhelms its radiated losses. Unfortunately, your electric water heater is still a net heat loss into the basement, albeit a little less than the boiler.

So, maybe you're saving a little. At the same time, I hope I never need to worry about problems on the scale of $150/year. When the boiler dies, I'll evaluate the most cost-effective system to replace it at that time. Until then, I don't see any substantial benefit in worrying about it.

The only possible exception to this would be the aforementioned HPWH. If you use your basement for a rec room, exercise room, etc., then it might make sense to have some free summer-months cooling down there. In addition to gub'ment reimbursements, which can make them very inexpensive, you could also save $100 per month (not per year) on dehumidifier usage. There's real benefit, there.

My perspective is that my oil burner is super old, and likely to have an issue or break down requiring a costly repair. Instead of running it year round, add a new/reliable device that does the same thing and saves money..and is perfectly silent.
And you don't have to pop the top off an electric hot water heater to scrub the carbon off it once a year.

If one thing goes wrong with your boiler, just to have someone look at it, you're talking $100. Fix something, another $100, minimum.

It makes perfect sense to me to have a nice new appliance that pays for itself, instead of a rusty old one that requires maintenance, that costs more money. I'll take that deal any day of the week.

 

[billb3]

My perspective is that my oil burner is super old, and likely to have an issue or break down requiring a costly repair. Instead of running it year round, add a new/reliable device that does the same thing and saves money..and is perfectly silent.
And you don't have to pop the top off an electric hot water heater to scrub the carbon off it once a year.

If one thing goes wrong with your boiler, just to have someone look at it, you're talking $100. Fix something, another $100, minimum.

It makes perfect sense to me to have a nice new appliance that pays for itself, instead of a rusty old one that requires maintenance, that costs more money. I'll take that deal any day of the week.

You were using an ancient oil burner that was likely at best 50-55% efficient (tuned up) to just make hot water ?

 

[moey]

A modern oil boiler that is not grossly oversized in most cases will make hot water cheaper then electric resistance. The math is simple btu's and efficiency. Most folks who switch to electric hot water heaters have a 20+ year boiler that is sized 2x what is required to heat their house or do not have a indirect hot heater.

 

[maple1]

I shared my real life numbers above. My boiler wasn't ancient. It would have been 20 years old last year, and had a nice Riello burner on it. It did not use an indirect though, but a tankless coil. Not grossly oversized. Cost about 5x the $$ to heat my DHW with oil than now with resistance electric.

My folks have a Buderus boiler & indirect, about 5 years old. Not oversized. They also spend a lot more money heating DHW with oil than I do with electricity. Not sure how much, I'll quiz them up next time I see them.

Would be interesting to get some input from others who heat DHW with oil, and have accurate consumption/$ numbers on what it costs them. So far we haven't seen any in this thread - and so far I have never seen anyone who has done both say that oil was cheaper. Standby losses, both radiating & up the chimney are the kicker.

 

[Ashful]

I can post my numbers tomorrow night, but it was close to 1 gal/day, at market price. Heat loss is not a big factor in my cooling costs, as I'm not air conditioning my basement boiler room, and the walls and floor seem to do well sinking the excess heat (my basement stays cool all summer).

 

[sportbikerider78]

You were using an ancient oil burner that was likely at best 50-55% efficient (tuned up) to just make hot water ?

...during the summer.

In the winter, it heats the house.

 

[WES999]

I was in the same position as you about 6 years ago. My older oil boiler with tank less coil was running about 1 hr/day,
burning 1 gal/day at a cost of about $100/ mo just for DHW. I found a nice 80gl electric water heater on CL for $50.
I also added a DIY solar water heater http://builditsolar.com/ . My boiler has been shut off for 6 years now with no problems.

Over the last 6 years the water heater has run for 1439 hours ( I have an hour merer on it) for a cost of $970
about $13/mo.

Over the last 3 months with good solar production, the water heater has run for 26 hr , about $6/mo.

A good choice would be to go to a HP water heater and get off oil.