Spitting thermostatic radiator valves

Jeremy_10

Basics: 4-story, 8-family apartment building; one-pipe steam; gas boiler about 15 years old. Basement mains are insulated. Third floor is warmest, followed by fourth, second, and first (coldest--basement ceiling has no insulation).

This winter, I tried replacing the standard radiator valves with thermostatic valves on some of the third and fourth floor radiators. I'm using Honeywell controllers with Hoffman valves, as supplied by State Supply. The new valves spit frequently. The old, non-thermostatic valves did not. I turned the pressuretrol to the lowest settings--1/2psi cut in and 1psi (or maybe 1 plus 1/2psi cut out). Didn't help (although the pressure gauge read 3 psi before the boiler actually shut down).

The design of these valves seems to allow condensate accumulation in the bottom of the connection between the radiator and the controller. The nipple that enters the radiator is not at the lowest point of this horizontal connector. I would think this water would be the cause of the spitting, but it's inherent in the design of the unit. It wouldn't be possible to pitch the radiators enough to counteract this.

Does anyone have any suggestions? Thanks very much.

Jeremy

nicholas bonham-carter

spitting trv's

i would concentrate on balancing the system so the trv's can be put on the shelf, or sent back to the supplier. here is the list of things to do in order of importance:

1.check your pressure, and make it 12 ounces or less! a vaporstat, and low pressure gauge may be a necessary, but worthwhile investment. your pigtail may be plugged right now and unable to "feel" the pressure.

2.check your venting on the basement steam lines, and double their capacity, so that steam arrives at the mains a few minutes after the boiler begins to steam- again a very worthwhile investment.

3.examine the difference between the radiator vents on the 3rd 4th floors. the 3rd floor vents must have more capacity than the 4th, but you want it the other way round!if the vents are the same you may have to put bigger gortons on the top floor to get the steam up the risers as quickly as possible.

4. if after this you have a problem with one radiator, then use a trv on that. i view them as band-aids, only to be used where all other efforts have failed, but they are NOT a substitute for proper function. an analogy would be oiling dragging brakes instead of fixing them.

5.check your thermostat location and anticipation. don't automatically think that setback will save any fuel, until the other problems are resolved. these old steam systems can be suprisingly..quiet...even...economical, in spite of prevailing opinion, as long as they are kept in tune!--nbc

bb_10

Vacuum Breaker

Do the Honeywell valves you installed have a vacuum breaker?

If not, they will no let air back into the radiator so that the condensate can drain back to the boiler.

Also, check to see if the pipes and radiators are pitched properly.

bb

DanHolohan

If this is one-pipe steam,

the TRV should be between the radiator and the air vent. Sounds like you're using two-pipe-steam TRVs on one-pipe radiators. That will cause lots of spitting and hammering because when the valve throttles, the condensate can't get out of the radiator.

Jeremy_10

Dan,

This is the thermostatic set-up I have. It's supposed to be for one-pipe systems:

HN1578 Honeywell Braukmann non-electric one-pipe steam valve. 1/8" IPM, W/1/8"Adapter & Bushing for the vent. The valve can be used with the remote operators or built-in operators. $50.74
HK1030 Hoffman 41 convector steam vent, non-vacuum, float type, 1/8"NPT straight shank, 10lb maximum, single non-adjustable port. Great for thermostatic one-pipe steam valves. $19.90
HN1500 Honeywell Braukmann self-contained temperature control for V100 series non-electric steam and hot water zone valves. The temperature range is 43-79 degress F. adjustable. $23.80

bb, they're called "non-vacuum." Does that mean they have a vacuum breaker? I don't know, but they should, since they're for a one-pipe system. Regarding pitch, neither the pipes nor the radiators have been changed, and the standard valves don't spit. To actually get all the condensate to drain from the body of the new operator housing would require a severe pitch on the radiators.

nicholas, if excess pressure could cause these valves (but not standard, non-thermostatic valves) to spit, then you may be right that the pressuretrol is not working correctly to cut off the boiler at less than 1 psi. Also, while the two mains are vented in the basement, the venting may not be adequate. Finally, I note again that the warmest floor is 3 and the coldest is 1, so to try to help this situation we have Gorton D valves in the first floor apartments.

It sounds like it will be worth a service call to check the pressuretrol and install more air vents on the mains.

If there are any more comments based on the above information, I'd appreciate them. Thanks so much for your help so far.

Jeremy

DanHolohan

Those are okay.

And by vacuum, I believe they mean that you can't use them on a vacuum system, which you don't have.

Do the air vents you're now using have the threaded part coming out of the bottom of the vent, or out of the side? These valves work best with vents that have bottom threads. The condensate needs to drain from the vent and back through the valve.

Jeremy_10

The new air vents have bottom threads to connect with the controllers. The old vents, of course, have side threads to go directly into the radiator.

DanHolohan

Supply valves

At the inlet side of the radiators. Fully open?

Jeremy_10

Yes, fully open.

nicholas bonham-carter

spitting valves

maybe moving the gorton d's to the top floor would even things out. it does sound as if the main venting could do with an increase in capacity.--nbc