Home>Discussions>INSULATION & HVAC>Best choice for new HW heater?
5 posts / 0 new
Last post
Best choice for new HW heater?

Hi everyone - first post from a new member. I've been a fan of TOH for years, been a subscriber to the magazine and sometimes a lurker on the website.

My 35 y/o oil-fired Weil-McLain furnace/boiler died yesterday. The boiler produced hot water for our home, and also ran our baseboard heat. I need to replace the furnace, but here is the wrinkle when it comes to choosing a HW heater: we heat our 2800sf home with wood during the Maine winter, and our furnace only heats the second floor... and even then, only on the coldest nights. It DOES heat the entire house if we go on vacation during the winter, but we literally use the baseboard system so infrequently that we need to purge the air from the system every fall as our baseboard pipes become air bound from lack of circulation.

I would rather not draw HW off the furnace if possible as it seems that we'd just have the same expensive setup: another oil-fired HW heater. I'm not sure which system (tankless, indirect, or standard heater/tank) will be the most effective/efficient. Also could use some advice on fuel - we have a propane tank for our range (but no natural gas availability), an oil tank, and 200-amp residential service. About the only thing I've ruled out is an electric tankless system. Currently have three BRs and two baths, planning on adding a master suite next year.

I'm leaning towards an indirect setup, but I'm not familiar with the pros and cons. Any advice you can give will be gratefully heeded!

Re: Best choice for new HW heater?

You can benefit from picking the brains of some local contractors. Invite 2-3 for estimates.

It seems that replacing your furnace with the same kind is the better idea, since you don't have NG available.

Re: Best choice for new HW heater?

The existing setup basically gives us an oil-fired HW heater, which runs several times a day (to keep the water in the expansion tank up to temp) whether we're using it or not. It's expensive, given that we don't really use the furnace for heat.

Any thoughts on an LP-fired tankless system?

Re: Best choice for new HW heater?

Hi seboeis,

It's unfortunate that you don't have natural gas as a fuel option, but there is still propane and fuel oil as available options; #2 oil is good & it has a lot of heating punch; the only minor disadvantages are the slightly higher cost & the annual cleaning (at least once a year) that is required to allow the system to function at its highest efficiency---you have a BOILER there, not a furnace.

It also sounds like you have a large lot & are able to rely on wood for a considerable amount of your winter heating, which must cut down on the heating expense considerably---is the location northern Maine or southern Maine, & have you had any past problems with frozen pipes in your forced HW system?----if so, there is a non-toxic propylene glycol (Home Depot/Lowe's) approx 2 gallons of which can be added to the heating system if you experience near-zero or sub-zero weather.

Sorry to hear that your Weil-McLain boiler recently died, but it does allow you the opportunity to buy a new boiler WHICH WILL BE MUCH MORE FUEL-EFFICIENT (if you decide to stay with oil) than the Weil-McLain----the one that died was probably giving you 70% efficiency, or less--- (meaning at least 30% of the burned fuel was going up the chimney to heat the great outdoors), where a new more efficient oil-fired or propane fired unit will give you 85% to 90% efficiency---the newer models are just that more efficient in burning fuel--it is also common to have seen 35 yrs ago the heating contractor install a boiler THAT WAS MUCH TOO LARGE in heating capacity for the heating needs of the house, thus burning excessive fuel---the new installation must include the boiler installer doing a MANUAL J HEAT LOSS CALCULATION to take into consideration how much heat the building needs so precious, expensive oil is not burned needlessly---it is often a good idea to firm up/replace any loose storm windows & add blown-in insulation to the exterior walls and attic of the house---R-13 required for exterior walls/R-40 for attic, (especially in an area like Maine) so that any heat produced by the boiler/ baseboards doesn't fly right out the house thru the loose windows & uninsulated walls.

You're assuming that your domestic HW (DHW) is stored in the expansion tank, when in fact it is stored in a 15' circular 1/2" diameter DOMESTIC COIL that extends coiled up into the boiler jacket & can produce only a gallon or so of DHW for bathing, dishes, etc.---as you noted in your post, this is a very inefficient way of making DHW, as the burner has to constantly fire thru the day & night to keep the water in the coil hot, whether it's used or not----a much better option would be to select a new propane-fired or oil-fired boiler WITHOUT the domestic coil & instead include a 30 gal. or 40 gal. INDIRECT HOT WATER HEATER (Triangle Tube, Crown Megastor, Amtrol & others) & set it up right next to the new boiler as a SEPARATE ZONE---the advantage of an INDIRECT HWH over your present inefficient coil is that the INDIRECT is heavily insulated & acts as a heat exchanger to store 20-30 gal. or so of DHW for showers, washing, etc.; you'll never run out of DHW--these units last for decades, since there are no moving parts, especially if you don't have hard water in your area---if you DO have hard water in your area, a water softening system for the water coming in from the well is recommended.

The expansion tank btw is actually a safety device---since water expands 3% to 5% when heated, the added volume experienced when the burner fires on a call for heat, would crack the pipes due to the added pressure of the expanded HW---the ET has inside it a flexible neoprene/rubber bladder that temporarily expands to prevent excess pressure in the system---should the ET fail (broken bladder/water-logged ET) there is a pressure relief valve (PRV) near the boiler that will open spilling HW on the boiler room floor at 30 psi to reduce the pressure until the ET can be repaired/replaced.

You should also consider setting up the 1st & 2nd floors as SEPARATE HEATING ZONES, using zone valves (inexpensive), but would require the re-piping of your HW distribution piping system (which could be expensive), ---ZONING the ENTIRE HEATING system would save more fuel & would make the different sections of the house more comfortable---each floor of the house would have its own T-stat, so you could control the heat for each floor---sometimes it's advantageous to also zone off the bedroom or other areas of the house with up to 5 or 6 zones each with its own T-stat to have better control of those areas of the house that can mostly remain at a lower temperature until heat is needed.

A propane-fired system would burn more cleanly & thus avoid annual & semi-annual cleaning bills, but would require a large tank to be installed somewhere near the outside of the house---you should do a fuel-cost comparison of both fuels to see which would be more economical in your case.

I strongly agree with dj that you should contact 3-5 heating contractors in your area to run some of these options by them & get written quotes so that in the end you will be able to make an educated choice as to which new heating system is the best for you.

There are many good boiler brands out there such as Crown, Dunkirk, New Yorker, Peerless, Slant/Fin, Utica, Weil-McLain & others.

Re: Best choice for new HW heater?

I forgot to mention oil-fired boiler combustion chamber design in my last post------if you opt to stay with oil heat for your new boiler, make sure you tell the installer that you want a new boiler with a "3-pass combustion chamber", and NOT a "pin-type combustion chamber"; the pin-type CC has a much greater tendency to soot up during the heating season due to (usually) unacceptable close tolerances between the cast iron sections.

The desired 3-pass boilers include the Biasi B10, Buderus G215, Burnham MPO, Crown Freeport, Dunkirk EV & Empire series, Peerless PRO & WBV series, Slant-Fin Eutectic & the Weil-Mclain WGO, among others.

In addition to the 3-pass design being free of soot-up problems, the combustion chamber of the 3-pass extracts more heat energy from the fuel for better efficiency & less fuel consumption.

Sponsored Stories

TV Listings

Find TV listings for This Old House and Ask This Old House in your area.