Home>Discussions>INSULATION & HVAC>One steam system to two forced hot air systems.
4 posts / 0 new
Last post
One steam system to two forced hot air systems.

I own and live in a two family home. There is currently one heating system for the whole house, steam heat with a gas boiler. The boiler is on its last leg and since we have to replace it anyways I'd like to split out the heating system so there is one system for each apartment. We've contacted several local heating contractors about getting quotes and haven't had much luck. Maybe we're talking to the wrong people but we've only received one quote and its for forced hot air systems.

So I have a few question about this:

What do you think about forced hot air systems?
Would just splitting up the current system to two boilers be a viable option?
Are there any good resources for finding local contractors? I've tried Angie's list but most of the reviews on there are for contractors that have done simple fixes not system installation.

Thanks in advance for your opinions and advice.

Re: One steam system to two forced hot air systems.

Splitting up the system is a viable option if money is not a problem. It could easily double the cost over the installation of one single boiler. Possibly even triple it. It depends on the flue, the piping and the location of the boiler. If you are wanting better temperature control, or better energy efficiency, that is not the way to get it. If you want seperate billing, that is about the only way to do it. Look up several residential boiler companies on-line and see who is the Rep. in your area. Burnham, Peerless, Smith, Columbia, to name a few.

Re: One steam system to two forced hot air systems.


These can be classified as "retrofit HVAC systems"; new heating/cooling systems that are installed in existing housing.

I must say I'm not a fan of continuing a steam heat system unless you intend to sell the property in the near future & opt for the least expensive choice of simply installing a new steam boiler.

This project should be left to the warmer months---it could well involve removing all the steam rads & perhaps installing a single forced hot water boiler with forced hot water baseboard with 3 zone valves (one for each floor & one for the domestic hot water tank)--the baseboard would be connected to the piping by plastic PEX tubing that is easily snaked thru walls & joists/studs---the zone valves (Google "taco 571 zone valve" to see a pix of this valve) would give each floor its own t-stat & involve the installation of only one boiler---I'm a big fan of forced hot water, because it's so flexible & provides comfortable heat; I think you'll be very pleased with this type of system.

It's possible that some of the old steam rads could be used in the new HW system, but they usually have to be sold for scrap.

Another possibility is a forced hot air/AC combo system that is known as the Unico system & involves one or two FHA furnaces in the cellar and 4" round flexible tube ducting that can be easily snaked thru walls & joists to be installed as ceiling registers and returns---the system can accomodate AC as well as heat, & is thus popular for that reason, as well as installation ease in existing finished structures.

Continue to contact as many heating contractors as you can (Yellow Pages "Heating Contractors"); you will have to find someone who has done this work before & knows the ropes--also contact the heating supply houses in your area (Yellow Pages: "heating--parts") & go in to ask the counterman if he can recommend anyone wo does heating retrofits in your area.

Also Google "2-family residential heating retrofits" (without quotes) or "2-familyresidential HVAC retrofits" (without quotes) for a number of sites dealing with this topic.


Re: One steam system to two forced hot air systems.

Forced air systems give you the ability to heat, cool, and filter the air, unlike steam systems. Some people like radiators, some don't have room for duct work, and some are historic homes and have to look period. If you have a choice, I would go with forced air.

Sponsored Stories

TV Listings

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