old two pipe hot water system

mark_s

This system has no circulator, house built in the 20's customer complains that it take a while for the top floor to get hot. can a add circulator. The house is a basement, 1st and 2nd floor about 3000 sq in total. semi attached.

Steamhead

This is a "gravity" system, the standard type of hot-water system being installed at that time. Circulators hadn't been invented yet. The boiler is much newer, maybe 1950s or 1960s.

I would bet that the pipes connecting the boiler to the original system do not support the flow rates needed to make it work properly on gravity. Some more pics of this part of the piping would confirm this.

I would do a heat-loss calculation on the house and, especially if the boiler is considerably oversized, recommend a new boiler. That one was made when fuel was cheap.

Where is the expansion tank on this system?

FranklinD

That system is a dead ringer for the one that was in a house my buddy bought in St Paul, MN last year. His was a HydroTherm boiler, looked very similar, ran like a champ.

He replaced it with a Buderus 85% sealed combustion boiler and a Bumblebee circ.

SWEI

We love these jobs. What are the fuel costs like there?

jumper

First thing is to consider high and low limit temperature on boiler. Circulator can help and is relatively easy to do. Smallest horsepower with no cut off flow. Don't forget a strainer. But I would do that as a last resort.

More difficult to do but superior in some respects is a vacuum tank at top of system. That involves an accurate and calibrated pressure gauge.

mark_s

Steamhead... i didn't see a expansion tank. Ill take more pics...

jumper...

1-what do u mean by no cut off flow? (no check value)?
2-why would a circulator be your last resort?
3-why is it superior to have a vacuum tank at top of system?

FranklinD ....
1-If the old boiler ran well why was it changed?

2-They didn't He replaced it with 95% boiler?

jumper

See head vs flow curves for circulators. Cut off means flow rate at which pump delivers zero head (pressure). You want a pump that does not do that.Otherwise the circulator may actually reduce natural gravity thermo-siphon effect.

If I can achieve satisfactory results without a circulator that's one less component that will eventually fail. Also it is thought that some water leaks through pump's seal.

If you can replace open expansion tank at top of heating system with a vacuum tank air can be eliminated. All hot water heating system work better with less air in the water.

Paul48

https://heatinghelp.com/systems-help-center/sizing-circulators-for-old-gravity-hot-water-systems?stage=Stage