Help! We recently installed a new boiler and pump in our 77-year-old home. The water pressure is great, but too much for our old boilers. They are incredibly hot and can't be turned off. Our plumber has been searching for new valves to fit to the old radiators, but without luck. Any ideas?

I am having trouble understanding the whole problem. If the radiators are getting too hot, I would think any standard ball or globe valve could be used to throttle down the water flow. Ball valves are trickier to adjust, don't have the angle built in, but have much less problems with the stems leaking, and never need new washers.

A better solution might be to reduce the rate of the boiler firing so the water didn't get so hot. That might be more efficient. It sounds like you may have been sold too large of a boiler. More isn't always better.

Hi Labman,
Thanks very much for responding. Apparently the water pressure is so strong that it just clears the old valves. The plumber had some new valves in mind that could completely shut off radiators and had individual thermostats, to boot. However, the old "American Radiators" stand about 3" off the floor -- the connectors and old valves are about 3" off the floor, too. The modern valves don't fit. He was talking about trying to prop up the old radiators on feet or looking for valve parts in Japanese catalogs. He has brought over two sets of modern valves which don't fit. In the meantime, he suggests we use radiator blankets to keep it from getting too hot and lowering the thermostat. So now the ground floor is barely 60 at night and it's still 75 upstairs. Originally we were hoping to be able to turn the heat off completely on the third floor when it's not in use. Now maybe we should just turn down the pressure on the new pump, if possible.
Thanks for your advice. I will pass it on to our plumber.

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Originally Posted by Mendotahouse

Hi Labman,
Thanks very much for responding. Apparently the water pressure is so strong that it just clears the old valves. The plumber had some new valves in mind that could completely shut off radiators and had individual thermostats, to boot. However, the old "American Radiators" stand about 3" off the floor -- the connectors and old valves are about 3" off the floor, too. The modern valves don't fit. He was talking about trying to prop up the old radiators on feet or looking for valve parts in Japanese catalogs. He has brought over two sets of modern valves which don't fit. In the meantime, he suggests we use radiator blankets to keep it from getting too hot and lowering the thermostat. So now the ground floor is barely 60 at night and it's still 75 upstairs. Originally we were hoping to be able to turn the heat off completely on the third floor when it's not in use. Now maybe we should just turn down the pressure on the new pump, if possible.
Thanks for your advice. I will pass it on to our plumber.

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your boiler must have at least a water temperature controller(((*** or there will be an explosion)))... if the hotwater temperature is improperly set the space's temperature will over shoot the stat's set point

Is this a steam system or hot water with a circulator pump?

If you have a pump, it is now a hydronic system. Did the plumber try turning the boiler water temp. down @ the aqua stat? What about partially closing the shut off valve at the boiler? There should be a valve before the circulating pump.

This makes no sense. If you have a hot-water based system w/boiler and radiators, it must have a pressure reducing valve in the water line serving the boiler from the house domestic water system. Most h.w. systems, in homes of up to two stories, run at a pressure of about 12 p.s.I. and the boiler's relief valve will open at 30 p.s.I. in any case. I cannot imagine a valve not being able to withstand the normal operating pressure. The circulating pump (and possibly the burner as well) are turned on and off by the room thermostat, and the water temperature is usually limited to about 180 degrees; thus I can't understand why you would be getting too warm, unless the thermostat was incorrectly wired. If it's a steam system you have, the pressure is even less; they normally operate at no more than 1 p.s.I.-2 in extreme cases. Relief valves on steam boilers are set to release at 15 p.s.I. Note that I am a Massachusetts-licensed oil burner technician with nearly 40 years experience in the heating and refrigeration trades.