Square D Pumptrol

I have a Square D Pumptrol attached to a pump and somekind of well that is a cylinder 21" by 7". A pumptrol is fairly simple device that measures water pressure via a rubber gasket. When it is too low, the pumptrol throws a switch which turns on a pump. My question is simple. Would anyone have such a device hooked up to a municipal water supply?

When the house was built in 1929 it was on well water and the heating system was coal fired boiler hooked up to a low pressure steam system. Very few private homes in the country use steam heat. Hot water is the preferred system for home heating.

At some point the well was required to be disconnected, and municipal water supply was hooked up. I have a sneaking suspicion that the steam boiler radiator system was left on the well, while the rest of the house was hooked up the municipal water.

It looks like the pipe are independent.

Water control into a steam system is very important. If the boiler keeps heating without enough water you have the possibility of a boiling liquid expanding vapor explosion (BLEVE). BLEVE is an explosion caused by the rupture of a vessel containing a pressurized liquid above its boiling point and the possibility of death is high.


If it is well water for this single use, contaminants may be interfering with the proper control of the water to the boiler.

Could the pump be feeding water from the muni supply into a reservoir that used to be the well? That would allow the pre-existing system to keep functioning, even though the groundwater that used to supply the well is now unavailable or unreliable. Just a guess.

Edit: Could the pump be used to raise the water pressure from the muni supply to the house?

Quote: Ayecarumba

Could the pump be feeding water from the muni supply into a reservoir that used to be the well? That would allow the pre-existing system to keep functioning, even though the groundwater that used to supply the well is now unavailable or unreliable. Just a guess.

Edit: Could the pump be used to raise the water pressure from the muni supply to the house?

I can't rule out any of that speculation, but the pump seems to be connected to a pipe that only feeds the boiler (not the regular water supply. All steam boilers have a low water cutoff as it is disastrous to keep heating a boiler if it doesn't contain enough water. This DOUBLE system seems to be triggering each other so that the boiler keeps turning on and off. At best it is a massive nuisance as you have to wake up every night and turn on the water or the temperature of the house drops below FIFTY because there is not enough water. At the worse case scenario, it could do major damage and have the possibility of an explosion to the boiler.

From you picture Paco the pressure switch (Pumptrol) seems to be attached directly to the motor of a jet pump. LH end of the motor is a pump. This type of pump can not pull water from a very deep well as suction will only pull water up so far. Sometimes a residence will require a pump connected to the municipal water system to raise the pressure if they have low pressure for some reason. It appears that you have traced the piping and this is not the case.

For the system to operate properly it would require a pressure tank somewhere on the downstream side of the pump. This tank would have an air bladder in it and allow the pressure to build up and then the pump to stop. If this pump constantly starts/stops within a few seconds either the pressure tank has a problem or doesn't exist. I don't think that your boiler would take enough water at any one time for the pump to operate at a reasonable cycle length.

Quote: kenarman

From you picture Paco the pressure switch (Pumptrol) seems to be attached directly to the motor of a jet pump.

Unfortunately, I can't find the cable to download photos from my camera, so I used the closest thing I could find on the internet. In my system the Pumptrol and the Pump are connected to some kind of reservoir (which is 21" diameter cylinder by 7" deep). The pressure builds up in the reservoir and then goes 8 feet straight up, and then gravity feeds into the boiler.

Yes the boiler is full in less than 2 minutes. Once the boiler is full of water it goes on (by itself sometime or by manually pushing the prime). After 14 minutes or so, the boiler runs out of water, and the low water cut-off (see below) on the boiler turns off the boiler. After 30 minutes or so, the cycle starts over.



To the best of my understanding, the low water cut-off is designed to be an emergency switch only. Under normal circumstances you would have enough water pressure so that only the thermostat would turn the boiler on or off.

There are less than 7 million homes in the USA that use fuel oil, and they are primarily in Northeast USA, The overwhelming majority of those systems run hot water boilers, with only a small fraction of single family residences running low pressure steam. Primarily multi family apartment buildings built before WWII run on steam systems. Some fraction of those homes used to have a well, and were converted to municipal water supply. It is difficult to find much information on the internet.

Your 21" reservoir is likely a pressure tank. As mentioned earlier they have and air bladder in them that contracts under the water pressure and maintains the water pressure after the pump quits. If this bladder is damaged or has lost it's charge of air it won't work properly. They often have a fill valve (similar to a tire valve) to recharge the bladder.

A possible reason the boiler was left on the well system is that municipalities often have rather stringent requirements on back flow prevention when a boiler is connected to the municipal water supply.

Seems very logical. The cylinder does NOT look like these tanks as it is much heavier and is only 7" high, but there is a vent feeding air into the top so it may be doing the same thing (just 1929 design).


The label says Weil "centrifugal ball bearing pump", but I can't find one like it on the internet.


Am I correct about the Low Water Cut-off on the boiler. I don't think that they should activate several times a day, but are more of an emergency device.

From the label you quoted Paco it does sound like a pump.

The boiler would normally turn on and off as it heats the water and cycle between 2 set points, a high and low temperature. The boiler should also have 2 safety cut offs one for low water as you have referenced and a 2nd for high temperature to prevent the explosion you have mentioned.

If the normal operating high temperature shut off is not functioning the boiler would continue to heat until it trips the overtemp high limit shut it down. If this is the case it should be looked at ASAP because if the high limit were to fail you would have your catostrophic failure. This high limit will often require a manual reset so that you are aware there is a problem.

Is there any chance that the pump is just your circulating pump for the boiler. There should be a pump that circulates the hot water through all the radiating devices in the house. This pump is normally controlled by the thermostat for the house. Some older and smaller systems might operate on convection/gravity only.

Quote: kenarman

There should be a pump that circulates the hot water through all the radiating devices in the house. This pump is normally controlled by the thermostat for the house.

This system is steam heat, it doesn't circulate hot water. That's what makes it so rare for a residence. Most steam systems run commercial buildings or apartments.

Two minutes to fill the boiler seems very fast .... is it truly full at that time or does the water flow simply stop?

Fourteen minutes to empty ? I don't know. Do boilers actually empty before being refilled or should water be added while low but not empty since I can't imagine you add cold water to a hot, but empty boiler.

At low water there would be a inflow mechanism but if that mechanism failed then the Too Low water alarm would activate.

Have you tried getting the names on these old pumps and comparing it with regional manufacturers of the time. The house may have been an institution at some time and that is why its steam, not water.