adding baseboard to 1 pipe system

ScottSJ

Have a question regarding the feasabillity of adding a fin tube loop into an existing 1 pipe system w/diverter tees.
Can I break into the loop between radiators and then enter back in the piping loop provided the boiler can handle the extra load?The existing house is aprox. 1025 sq. ft. It has CI radiators in the house and a 100,000 input boiler.The addition will bee aprox 450sq.ft.

Tony_8

bbd & rads

You can cut them in. I like B&G tees because they get better flow out the branch, but you MUST use them in pairs.

You probably have enough boiler. Size your bbd for a cooler than normal temp (180) as rads will run cooler than bbd. If you size it for 180 you probably won't have enough. The solution could be to zone it seperately from rest of house.

Steamhead

I wouldn't mix fin-tube and cast-iron

on the same zone, they behave very differently.

Why not make the addition a separate zone? This will give you more control over where the heat goes. 450 square feet is a bit less than half of 1025, and is enough that I think the separate zone is justified.

This would be a good time to change to Pumping Away, if you're not doing so already.

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JacktheShack

Adding baseboard to one-pipe system

Scott,

You didn't mention if you will be adding the baseboard ABOVE or BELOW the main, or if you did a heat loss calculation for the new area to be heated (baseboard heats @ approx. 600 btu/hr per foot @ 180 degree boiler temp.).

You can probably cut the new section into the main, but it may run too cold, especially if it is installed BELOW the main, since the hot water in the main will tend to stay buoyant, while the cold water below the main refuses to move; at this point you would still have the option of making a separate zone, as other respondents have suggested.

Be sure to read the excellent article on this website on exactly this issue by going to the main menu & clicking on HEATING Q & A: then on DIVERTER TEE HOT WATER HEATING; this is Dan Holohan's chapter from his book "How Come?" that explains how diverter valve one-loop piping works, & the importance of pumped water taking "the path of least resistance".