Unwanted gravity circulation

Etienne from Montr

Hello,

I hope someone can help me with this. I'm the owner of 2 60 year old duplex equiped with a hot water/oil heating system. The furnace is 10 years old and is working properly. But since i replaced one of the 2 pumps (the house is seperated in 2 sections) i'm faced with unwanted natural circulation that's very inconvenient during the first weeks of heating and when springs comes.

I checked the valves and from what i can see, the only valves installed are Thrush gravity control valves dating back to the time that the system was gravity controled. (but i'm not 100% sure the valves are really gravity control valves). The maintenance technician thinks that the valves can work as antigravity valves if properly adjusted. Is this true ?

If the current valves can't do the trick, and since my furnace works to keep its tank water always hot, is the only solution to install a antigravity flow valve ?

Thanks for any help.
Etienne St-Cyr,
Montr

Joe Billow_6

Check

Is this your valve http://www.thrushco.com/pdf/992005115113_website changes.pdf. The link has instructions on how to adjust the valve. If this is not the same you may have to install a flow check, like Taco sells http://www.taco-hvac.com/en/products/Flo Chek/products.html?current_category=183.

Etienne from Montr

Here's a shot of the valve

Thanks for your tip Joe,

I added a shot of the actual valve. Basically, there's a lever with a choice between "OPEN" and "THERMAL". It's currently set to "THERMAL". Will changing the setting to "OPEN" transform the valve to a check valve... i doubt it...

If anyone can comment, i'll very much appreciate it.
Etienne

Joe Billow_6

I think, but I could be wrong, that in the thermal position the valve acts like a flow check and when in the open position it allows gravity flow.