Best method to prevent convection in pipes

zeke

> I am having a new water heater installed for my <BR>
> small radiant heating system (350 sq feet of <BR>
> flooring). For the past seven years, convection <BR>
> has been a problem causing warm floors when I <BR>
> don't want them. A check valve just didn't do <BR>
> the job, for some reason. The circulator is a <BR>
> Grundfus 3-speed with a built-in check <BR>
> valve.<BR>
> <BR>
> With a new installation, I spoke to the <BR>
> plumber who said that a heat trap with a loop of <BR>
> pipe would do the job fine. I want this done <BR>
> correctly and would appreciate your <BR>
> insights.<BR>
> <BR>
> How would you radiant heating pros <BR>
> do this? Should the circulator be circulating <BR>
> out from the hot side of the tank into the <BR>
> heating loops? <BR>
<BR>
The natural convection flow is in the same direction as the circultor flow so a gravity check valve will not totally prevent the flow. I would install a spring loaded check valve with enough force to stop the nat convection flow.
The amount of spring force to stop this flow is the difference in water density of the hot leg and the cold leg times the area of the pipe times the height of the heater to the boiler.

Dave_4

Best method to prevent convection in pipes

I am having a new water heater installed for my small radiant heating system (350 sq feet of flooring). For the past seven years, convection has been a problem causing warm floors when I don't want them. A check valve just didn't do the job, for some reason. The circulator is a Grundfus 3-speed with a built-in check valve.

With a new installation, I spoke to the plumber who said that a heat trap with a loop of pipe would do the job fine. I want this done correctly and would appreciate your insights.

How would you radiant heating pros do this? Should the circulator be circulating out from the hot side of the tank into the heating loops?

Eric_8

Was the check valve a spring type or a swing type?

Unknown

We've had a few circulators

with built in check valves get hung up with system sediment . That would be the first thing I'd check . For the handful of problem jobs that had true heat bypass ( circ and weighted flow valve on the supply pipe ) , we either used a larger size flow valve on the supply or a separate weighted flow valve on the return pipe .