Domestic Furnace Heating Efficiency

A few points. First, your payback on a new system will be longer than the time you plan to remain in the house. Second, you don't want to ever shut your old system down for a number of reasons. It will tend to corrode if not used, when you do turn it back on there will be a thermal shock that can cause it to leak, and your gaskets may dry out and crack. You should turn the aquastat down to a lower temperature but keep the system on-line. And lastly, much of the efficiency gain from a modern system comes from the fact that there is less heat loss around the boiler/burner. This means your basement workshop will be cooler. If you need to add a new heating zone to heat your basement you will not be a happy camper.

First, your payback on a new system will be longer than the time you plan to remain in the house.

That's accurate. With my initial post so long already, I elected to leave out a funding program in NJ whereby the State gives homeowners a zero interest loan for home improvements, You make no payments towards the principle until the title changes hands at which point the entire amaount comes due. Purchasing a new heating system with current doillars and then paying off the loan with dollars worth less (assuming there's inflation) makes the upgrade even more tempting and of course the extra value to the house has to be considered. Combine this with Federal energy incentives and the financial viability gets even better. That's an assumption however which is why I must either find a spreadsheet devoted to this or confer with an accountant.

Second, you don't want to ever shut your old system down

The main system would not be shut down, nor would it be drained. The aquastate would be turned almost off so that any demands for domestic hot water would be satisfiued by the tank-less unit. As things stand now, the main system is constantly going on in response to the aquastat. Most of the summer time the boiler runs to offset heat losses for dosmestic water that isn't being used. It makes little sense to run that big boiler during the day, when I am not home, to heat all that water in the main unit just to supply how water that won't be used. Had I purchsed a seperate conventional hot water heater, gas or electric, as most people do, the same operational scenario would apply.

The lower temps in the basement could be a concern however because I do a lot of composite fabrication. I make large parts for aircraft applications and large aperture telescopes.

Lower ambiant tempoeratures means supplimental heating must be applied to properly cure the parts. That, however, has been an issue anyway, especially in the winter when parts curing overnight have to be helped with infra red lamps when the boiler goes into sleep mode for the the night.

I'd overlooked this. Thanks for reminding me.

Lower the setpoint on the aquastat to 110F while runing the furnace year round.

Guest wrote:

"Lower the setpoint on the aquastat to 110F while running the furnace year round."

Yes! Exactly! The furnace will still run in the summr time but not nearly as often and for not nearly as long. At 110 degrees, the temp of water it feeds to the tank-less unit will not need as much fuel to raise it's temp to what is needed for use.

Thanks

L.J.

You just described my house

I wouldn't change anything, if the furnace is an issue for sale of the house deal with it as a credit then.

I've added a 20% mixture of soy oil to mine and realized increased efficiency as the soy reduces the sooting of the heat exchanger. I'd put odds on the oil burner to out perform the tank-less unit the expensive one's are at 80% or less efficiency.

My neighbors old boiler cracked because he shut it down and didn't prepare it well. He replaced with an high efficiency LP boiler, It's costs him more in LP than he paid in oil.

Use the money to expand the basement; increased square footage will pay back.

A spreadsheet should be available from HUD.

Hi Bwire!

My response to Welderman covers somethings I think you'd want to know. As for the efficiency of the tankless unit. . . . that may be a valid issue. However, since it doesn't gets used much any way and eliminates the constant needless cycling of the main boiler caused by the aquastat, the savings are legitimate, reduced efficiency notwithstanding.

Expanding the basement is too costly, too time consuming and would rob me of time I need for other work in the shop as well as elsewhere.

Thanks for the post and for the quote from Eric Hoffer. Glad to see others appreciate his wisdom. It's the True Believers in today's political climate who bother me.

L.J.

The key factor of efficiency and value for resale is insulation, also qualifying for the "energy star" gives rebate 30%.

Actually I replaced the old boiler for steam with a oil fired hot water tank-less model from Hydro-Therm it's fairly efficient uses about four gallons a day when the outside temp hovers around -22°F is not part of the domestic hot water system.

If I do it again I'll pay attention to micro-boilers

This winter I'm using a cheap boxwood stove and burning shelled corn at a bushel a day to heat the basement which should keep the boiler piping toasty

Hi Andy. Hi Bwire!

I love fireplaces and gave a lot of thought to putting one in, if not for the heat, then simply for the ambiance. To do that, however, I need to get special permits. It ceased to be of interest, especially when they told me that the house would be reassesed and I'd see a tax increase.

I've an old, unused chimney in my Living Room. I could use that I was told but might have to drop in a new liner. That's when I gave up on the idea.

In my next home for sure!

Thanks, both of you

L.J.

The good point is that a pellets oven does not produce any tar or creosote. In fact it only produces a small whiff of smoke as it starts up, otherwise nothing that will distill out in the chimney like a wood fire can and does.

The PO burns cleanly.....very important for the environment...

So you don't need a liner......I am running into my 4th winter, no need for one....

Also we have a nice glass door that allows us to see the flames.....

May I recommend an alternative, buy a pellets oven and burn pellets to give the house a good basic heat source, which will cause the heating to shut off earlier or not switch on at all....

We did that 3 years ago and have not regretted it once.

Make sure that if you do this, that you avoid certain makes like Amaizablaze(?) or similar, is one that arrives on CR4 with problems far too often........

You need one with an "up and over" pellets delivery, never one with a horizontal delivery, no matter what the salesman says.......

Take it with you when you sell, or get its price tacked onto the house price!! They are simple to install and to keep running....you will never regret it.

Keep the old heating system in parallel....

If you a planing to sell in the next couple of years, do nothing. As you will never get the payback. The most cost effective thing you can do is install a reset ratio controller. This will minimize your energy use, as it sets the boiler loop temp based upon outdoor temperature and heating demand.