Hot Water Loop/Steam Boiler Question

John_23

I found a steam boiler with a hot water loop that heats the first floor of a residence. Steam does the 2nd floor. It has been having major problems with the bearing going bad in the pump every 2 years or so.

It doesn't have the bypass loop from the return to the supply. And I am looking to install it. It will be my first ever. The question I have is this. I note in Dan's drawings that the bypass comes in from the return as soon as the supply piping comes out of the bottom of the boiler on a horizontal plain. Is this crucial/necessary to doing this? I would if I could, Be easier.....just move the pump up and bring the loop into a tee where the supply goes up to the pump itself. Thanks for your help in advance this is a great place to learn about hydronics.

Plus any other tips about this would be appreciated

Thanks again

Iron

Unknown

Sure

You can do it that way if you keep the tee and pump flanges below the water line of the boiler.

The only pressure that the pump seal sees is the pressure developed by the boiler water height ABOVE the pump seal. Pressure, and NOT suction at the seal is what keeps it lubricated.

After you install the bypass, the water can be kept below steam temperature (which hasn't got much seal lubricating properties) at the pump inlet.

Another thing you should do is install a temperature and pressure gauge on the INLET side of the pump. Then you can open or close the bypass to get water at the right temp AND you can see if the pump inlet goes into vacuum. If it does, you might throttle the return connection, near the bypass tee, to add some head (back pressure) to the pumps job, and it might not go so far into vacuum. Vacuum is eating your pump seals, most likely. It wouldn't work at all if the pump were on the return.

Noel