Remove Zone Valves

tcnjdeluca

Hello, I have a steam heating system with 2 zones. Each zone is controlled by a mechanical valve. One is for the main house the other for my wife’s therapy practice’s office (about 900 square feet). One of the valves looks fairly modern the other looks ancient (main house). I came home to find the heat for the main house not working today. I noticed that the motor running the valve seemed louder then usual a few days ago so I went down saw the valve was shut and gave it a wack. The motor started whirring away and my heat came up. I greased up the levers and linkages and it appears to be working for now. I was considering repairing it myself since it seems it’s the old 24v motor that’s going not the actual valve but after doing some reading it appears that these steam zone valves are not a good idea at all. Should I have someone come out and remove them and tune up the system? Thanks for your advice.

Jamie Hall

Steam zone valves have advantages -- and disadvamtages. The most obvious advantage is that one can cut off the heat to an area when it's not wanted. This does save fuel and money... but it brings up one of the two disadvantages: if the zone which is cut off is sizable, the boiler winds up quite oversized, and will cycle much more often. Is this a problem? Not really -- some loss of efficiency, some additional wear and tear on the boiler.

The real problem with zone valves shows up if they are not sized and piped correctly. On sizing, they really must be full port gate or ball valves on most systems (high pressure, particularly superheated, steam is a little more forgiving. Otherwise one loses a lot of heat and therefore fuel even when they are open. The other problems have to do with the returns, and with handling condensate at the valves. There really must be a condensate drip on the downstream side of the valve, and if the system is parallel flow -- or almost all two pipe systems -- there must be one on the upstream side as well. These need to go to a wet return. In most cases, with low pressures, you don't have to worry about valves on the returns -- but one does need to keep in mind that there will be no steam pressure downstream of the valve, so you need to have enough headroom that water won't back up into either the dry return (if any) or the steam main.

Bottom line for you, though, after all that verbiage, is that if the system you have is working satisfactorily, and if you like the way it runs and can be zoned, there really isn't any good reason to take the valves out. With the valve that was stuck, before you swap out the motor make sure that the problem wasn't a sticking linkage or actuator.

pecmsg

wife’s therapy practice’s office is 900 Sq Ft

Whats the rough Sq Ft of the second zone?

tcnjdeluca

The main house is approximately 3,000 sq ft

pecmsg

tcnjdeluca said:

The main house is approximately 3,000 sq ft

Thats a HUGE load difference.

Maybe set it up as a Slave system. The main house controls the boiler, the wife's office then receives heat but can turn off if too warm.

tcnjdeluca

Yeah that makes more sense to me, I don’t really understand the point of the valve on the main house. Then again I don’t really have a great understanding of steam systems. The problem is neither do any of the local contractors.

Steamhead

Where are you located?

tcnjdeluca

Central New Jersey near Trenton.

Jamie Hall

If you want top notch help, try @EzzyT .

tcnjdeluca

Okay, I could not get a contractor out till Wednesday and the heat got stuck ON today which worried me. So what I did was let the motor crank the valve to the open position on the main house. I removed all power from the motor. I removed the limit switch that activated the boiler and wired the boiler directly to the thermostat. So now the main house essentially does not have a valve. The office is still on its own valve that can also activate the boiler which I suppose could theoretically cause some overheating in the main house. It would be simple to remove the limit switch so the office valve did not turn on the boiler, essentially only turning off heat if the office got too hot. But I think I am going to leave it as is for now.

Does anyone see any flaws with my plan?

I promise I am going to get a steam pro out ASAP to sort this all out.

pecmsg

What limit did you by pass?

tcnjdeluca

So the way the system worked is that the thermostats activate the motors that open and close the valves. As the motors fully open the valve, the linkage presses a limit switch. This switch is what turns on/off on the boiler. I left the valve in the open position and removed the wires from the limit switch and wired them to thermostat, so the thermostat now turns on and off the boiler directly. I did not change any of the other systems.

Jamie Hall

Should work just fine. Not to worry.

pecmsg

End Switch not a Limit thats fine