Combination Boiler for Radiant Heat

Rodney Summers

BUT, it's not a great idea to install a large oil boiler and only use maybe 1/3 the capacity. If you're WH is oil fired, I would get the indirect tank now so you don't have 3 oil burners and 3 vents to worry about. Put the hydro air coil in later. Size the boiler to the heat load and get priority/outdoor reset controls for it so you don't oversize the boiler. If you had nat gas, you could get a modulating boiler that could handle the smaller load to start. If you don't get the boiler, option # 2 would be the next best.

Michael Singer

Combination Boiler for Radiant Heat

All:

I have a 1936 Colonial, located in West Hartford, CT that is currently heated and cooled via a forced air system. The furnace is a 20+ year old Williamson that does a very good job (notice I did not say a very efficient job) of heating the house. Cooling is provided via a 4-ton unit and a coil that is powered by the air handler that is part of the furnace. We are adding a 500 square-foot addition to the existing 2500 square foot house and need some help figuring out how to heat and cool the new space.

My ideal solution would be to heat the space using a radiant system and cool it with a stand alone, ceiling-recessed ductless system. My main problem is that the three HVAC companies that I have had look at the addition have come up with three different heating options. They have all agreed that the ductless split is the best way to cool the new space (Mitsubishi Mr. Slim PLH-18AK but I am open to new ideas.) I would like to open this up to the Wall and get some practical advice as how to proceed. Here are the options (from Cheapest to Most Expensive):

1. Replace my domestic hot water heater with a new, larger water heater and run the radiant system off of the new unit. Use a staple-up system for the radiant (accessed via the crawl space) below the addition.

2. Replace my domestic hot water heater with a combination boiler and domestic heater (a tank-in a tank system?). Run the radiant off of the new combination unit and install the piping in between the sub floor and the finished floor (hardwood) using the pre-routed sheets of 1/2 inch plywood.

3. Install a full size boiler, big enough to eventually take on the entire heating, domestic hot water and radiant systems of the entire house. Use it to run the radiant system for now, and hook up a hydro-air loop when the furnace goes and indirect hot water heater when my existing gas fired water heater dies. The radiant heat would also be installed between the sub floor and the finished floor (hardwood) using the pre-routed sheets of 1/2 inch plywood.

I want to be smart about how I spend my money and factor in that my furnace may be on its way out BUT I do not want replace both systems now. I am fine solving my immediate need for the radiant floor heat for the addition, and replacing the Williamson with a new forced hot air system down the road. I just want to make sure that I make an informed, intelligent choice while considering all my options. Sorry for the long-winded post but I wanted to try to describe the situation as best as possible.

Any help/advice/comments/recommended contractors would be greatly appreciated.

Thanks for your time.

Mike

Al Letellier_9

choices choices

For what it's worth, Mike, here's my opinion:
Forget #1...a water heater is a water heater,not a boiler
#2 is a good idea because it will save you money in the long run and will be efficient. I like the radiant approach. We do a lot of the Quik Trac radiant and it's the best way to go, especially if you're using hardwood.
#3 is OK but the boiler will be way oversized for the job at hand now. I like the hydro-air approach. Replace the furnace with a fan coil unit and heat it with FHW
Option 2 could be the best solution from what I understand of your system. If you stay with oil (good choice), and select the right boiler, you could always expand it later by adding a section or two if you go hydro-air.

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