steam radiators & saving energy

Adam_13

Turning off radiators certainly makes a difference. I'm just a homeowner here, but before I really got into steam I used to think the radiator in the room with the t-stat was the most critical. In other words, I thought that since that room controlled the heating cycles, opening more or less radiators (in other rooms) would not make a great difference in run time and fuel consumption. However, this is not correct. You're really paying to bring return water back up to steam temperature. Adding more radiation increases the amount of returning condensate and generally lowers return water temp. Thus it will take more BTU's so to speak from the boiler before that water turns back to steam and is sent out into the system again. I believe I'm correct in saying this though my wording may be a little off. Any corrections from the proffesionals out there is greatly welcomed. Anyway, the bottom line is that it does make a difference, and this difference should be proportional to connected load as another contributor has already mentioned. I believe the on-off-on-ff of your burner is a seperate issue again as others have already addressed. Hope this helps -Adam Just a few more considerations; obviously turning off lots of radiators will cause the boiler to effectively be way oversized, possibly causing short cycling problems. However turning off a few radiators here and there should not make much difference. The savings in fuel would be much greater than any problems this might cause with the system. There is still one more "but" though. Turning off radiators can affect the heat loss of rooms adjacent to the "cold" rooms. Depending on how oversized your radiators are, this might not be a problem. Otherwise, at best this might just affect the comfort of the adjacent rooms, but if one of those cold rooms is next to the room with the t-stat it could cause the system to run for "longer-than-necessary" periods of time. Steams systems are SYSTEMS. Systems are dynamic and everthing affects everthing else. You just have to play around a bit to find out which arrangement works best for you. Sorry for the long winded response, I just got home from class. Good luck -Adam

lane

steam radiators & saving energy

This past week I had routine service performed on our boiler (1 yr old weil-mclain). I had several of the steam radiators turned off in rooms that we don't use in an effort to reduce the gas bill. My thinking: fewer radiators would require less steam and therefore less gas to create less steam. The service technician said that this was not the case. He said that the boiler was sized for the house and that it was actually less efficient to turn off some radiators - that in some way the boiler had to work harder?? So now we have all the radiators fully open and turned on but I'm struggling to understand how I'm using less (or no more) gas. Can someone please confirm, deny or help me understand this? Thanks.

Steamhead (in transit)

He was probably thinking

that if enough radiation was turned off, the boiler would short-cycle. Short-cycling is pretty wasteful in itself. This is where a stage-fired boiler would shine, as it could drop to low fire when a few ounces pressure was built up.

But American boiler manufacturers don't seem to want to sell steam boilers with this fuel-saving feature in residential sizes. I have a hard time understanding this- whoever comes out with this first will sell a LOT of boilers.

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TONY_22

I'd be surprised

I suppose there might be some scenario where a system could short-cycle to the point where truning off radiation would actually increase the fuel bill, but it is hard for me to imagine what it would be.

I track oil use vs outside temp on a daily basis, and in my case, there is a significant fuel savings when I turn off radiation in unoccupied rooms. In fact, fuel usage is pretty proportional to the amount of radiation connected. In other words, when I have my usual load connected (300sq ft of radiation), I use about 0.18 gallons per degree day. When I turn on the radiator in the guest room, which is about 30 sq ft (a 10% increase), lo and behold, my oil use increases to about 0.2 gallons per degree day (again a 10% increase).

The disclaimer here is that I have a very old and oversized boiler, but I think you'd really have to get into an extreme short-cycle situation to not save fuel turning off radiation.

Jim Franklin

How do you track oil use on a daily basis? I'd like to do this...

thanks,
jim

TONY_22

oil use

I just use an hour meter hooked up to the burner. I read it every morning on my way to work (when I remember). I know the gph from the nozzle size and pump pressure and I can correct any error every time I get a fuel delivery. Error is usually less than 2 gallons on a 150 gallon delivery. I got my hour meter out of the trash at work, but i think there are a lot of options under $20 if you shop around on ebay etc.

I'm currently playing with monitoring stack temp and that seems to be pretty accurate as well and is more automated. I like to check on my boiler every day anyway, so going down to do the manual reading isn't a big deal.

Jamie Hall

Amen

where do I sign up?

Jim Franklin

Pressure difference?

The nozzle (new) is a .75-70 B according to the invoice. This'd be .75 GPH?

The pressure on the mfg label is 140 psi. SHouldn't this always be the same. taking it out of the oil usage equasion?

I'd be curious to hear more about the stack temp monitoring...

thanks,
jim

Steamhead (in transit)

Nozzle rated capacities are determined

at 100 PSI. For many years this was the standard pressure.

But we now see quite a few burners where the manufacturer wants a higher pressure. Yours is probably one of them- what make and model is it?

At 140 PSI, a 0.75 GPH nozzle will fire 0.89 GPH. You will probably find that value on the boiler's rating plate.

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Dave_4

why is short cycling inefficient?

I need to understand this because I recently put a vaporstat on my new boiler and the system is not very tight so it loses pressure pretty quickly. It cycles back on within 20 seconds of going off on less than a pound of pressure.

So am I hurting myself by setting the vaporstat so low? How could always on be better than on-off-on-off? Is it bad for the burner? Does it take extra oil to light the burner?

Thanks,
Tim

Steamhead (in transit)

It takes more energy

to start up a burner than to run it constantly. Also the start-up and shut-down have always been the dirtiest periods of burner operation. This has been improved greatly with the adoption of solenoid oil-delay valves and other improvements, but excessive starts and stops should still be avoided where possible.

On your system I'd first look at whether the steam piping is properly insulated. And if the boiler is that new it may need cleaning. Dirt in the boiler can interfere with steam production, causing production to stop suddenly when the burner shuts off rather than tapering off.

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Jim Franklin

Burner model

It's a Beckett AFG. DR802 is on there in big letters too. The mfg plate lists the range of nozzles it'll work with but I didn't see a nozzle/pressure chart.

Steamhead (in transit)

OK, what boiler

is it installed on?

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bob chapman_2

efficiency versus consumption

Your technician is probably correct that the furnace runs more EFFICIENTLY with all the radiators turned on. That's a whole different question from how much energy you're consuming. With some radiation turned off, you may well be running less efficiently, but at the same time using a lot less energy.

Jim Franklin

Boiler is

a DUnkirk 3ES1.35, 2 years old.

Chris (senior svc tech)

rad control

why don't you try installing Danfoss valves on all your rads. You would be able to control each room individually and dial in the exact temp you want. As for the vaporstat question you MUST fix all your steam leaks, or you will rot out your boiler due to fresh water make up. Here in NYC we see (and replace) tons of rooted boilers due to this problem. Last year we took out a 5 yr old WM 780 where the tops of 5 sections were completely gone. You could install a water meter (like Sensus) or Hydrolevel VXT with built in meter. Vaporstats are a much better choice than a P404A, or an L404A. Tightness of piping is most critical.

Joe K_2

Tightness

Hello,
What do you mean by 'tightness' of pipes? What kind of leaks do you notice?
Joe K.