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wetech 02-05-2013 11:50 AM

Adding an optional bypass to hydronic baseboad
My house is heated by an oil fired boiler feeding 4 zones of baseboard: 1st and 2nd floors, basement, and a room above the garage. The 1st floor loop includes about 20 feet of baseboard in a sunroom that we don't use in the winter. We keep the room closed off from the rest of the house when not in use.

I recently did a Manual J calc on the house, and found that this sunroom is about 20% of the heat load of the entire home and contains about 10% of the baseboard. I'm looking to save some $$$ by not heating this room at all in the winter, but would still like the option of heating it in the fall / spring. Would the following solution work ok?

1) Put a ball valve on both the supply and return pipe where it branches off for the sunroom in order to isolate it from the rest of the loop. These are only separated by a few feet in the basement.

2) Within this now isolated loop, add a valve with hose connection in order to drain / fill the loop as needed.

3) Add a connecting piece of pipe to complete the loop, also with a ball valve.

Best attempt at a before / after diagram:


.......|......... |
.......|......... |
.......|......... |
.......|......... |


.......|......... |
.......|......... |
.......h......... h
.......*......... *
.......|......... |

I know the best solution would probably be to remove this room from the 1st floor loop, and put it on its own zone. But I don't want to go through the added expense.

Bondo 02-05-2013 05:36 PM

Ayuh,.... What you've drawn out will surely work,....

Bein' able to Drain it is the most important thing,... it'll freeze, 'n split otherwise,...

Yer boiler should be plumbed for make-up water, for when ya put it back into service....

If there's low points in the loop, ya could put a drain on 1 end, 'n a shrader valve on the other, 'n Blow it out with compressed air...

beenthere 02-05-2013 06:56 PM

While your idea will work. Its also not a good thing for the boiler itself. Fresh water is an enemy of a hydronic system.

Might want to make your bypass, but make it out of 1/2" and don't close the valves. This will reduce the amount of water going to the sunroom, but keep it from freezing the pipes.

wetech 02-06-2013 12:25 PM

Thanks for the feedback. Good point about the fresh water. I think I'll drain the loop for the room and just leave it that way.

Missouri Bound 02-06-2013 01:31 PM

What I would do is create your bypass as you plan, but incorporate a zone for that space, with it's own thermostat. That way you can set the thermostat as low as you want, perhaps at 40 deg. and you won't have to worry about freezing and turning on the heat will be a simple thermostat draining would be necessary either.:yes:

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