Flow controls

Joe_10

Problem cold home. Has radiant floor installed 1975. Designed by an engineer. I saw the original blueprints. 3way honeywell zone valves control flow. A griswold valve on the feed to each zone on the return there are griswold flow control valves. On some Zones the supply is hot and the return is cold for at least two weeks those rooms are heated. Some zones have lukewarm supply and return I assume that that is beca these rooms don't have heat. Boilers were replace in Dec. to correct this problem. There are three way valves near boilers that have been disabled that were originally to control temp in the loops to zones. Each boiler is connected to five zones. The question is can the flow control valves be plugged or in some other way severly restricting flow. Or are the Taco 007s to small to push through all of the flow controls. I have no experience with flow control valves and am the third or fourth company to look at this this year.

Tom Anderson

There could be many reasons for your problems, but the first thing I would look at are the condition of the Griswold flow control valves. They will indeed foul if not properly protected by a suitable strainer. A 30 mesh strainer should be applied upstream of the flow limiting device, if there are none now.

Open them up, inspect the stainless steel internal cartidges. The ports should be fairly clean and unrestricted with crapola.

I will also add that in my experience, more than 80% of the design engineers, as well as similar percent of mechanical contractors do not understand the concept of why these things are needed, especially where variable flow can occur, and how they work, esopecially at part load. Simply put, a pressure independent automatic flow control valve, such as Griswold, does nothing at all except when the water flow wants to exceed the specified gpm. That is good.

I can't tell you how many times I have seen facility maintenance personell and consulting engineers condemn auto flow controls as "restricing the flow", when in reality, they are simply doing their job, and the valve has a big pressure drop across it because of an overheaded pump or improper design, especially in paralell chiller/boiler setups.

Hope this helps.

Eric

supply lukewarm??

The reason for 3 way valves is to have constant flow and not worry about balancing and pump rising on curve.

With constant flow the supply to all zone inlet to 3 way valve should be hot. Only reason not is no flow.

What are the bypass temperatures like?

If hot supply and hot bypass and hot retun and cold zone. Bad thermostat signal.

If hot supply and cold bypass and cold return. You are heating something in zone. If return is very cold is also a signal of low flow, but some flow.

If cold supply no flow.

Joe_10

Thank you

This gives me a solid start. There are no strainers in the system. I will start with checknig the flow controls and cleaning them and install strainers.