Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Thermostatic Radiator Valves

Unknown
Unknown Member
in THE MAIN WALL
One caution is to watch out for tall risers that feed TRVs with no way to vent the top of the riser into the return (crossover trap).

When a TRV shuts off at the top of a riser, the riser cools and fills with water FROM THE TOP DOWN!!!! Just like a drinking straw. When the TRV opens, there is a column of water that the steam can't lift, and that won't drop down into the main. It acts like a frozen pipe, which it would eventually become.

When you shut off the system, it cools down and the water falls back to the main.

When it runs next time, a different riser does it, but exactly the same symptoms. It'll drive you up a wall!

Crossover traps at the top of the risers cures it. It'll pay for itself in comfort and saved fuel.

Noel

Comments

  • Charlie_9
    Charlie_9 Member Posts: 4
    Thermostatic Radiator Valves

    I'm looking for advice on the wisdom of installing TRVs on my two-pipe vapor system. Can and/or should it be done? The system, installed in 1929, has Hoffman controls. Is there a TRV that can be installed directly on the original Hoffman #7 valve, or does the whole valve body assembly need to be replaced?
This discussion has been closed.

Categories