Steam system with a water loop and poor flow

Ron R

Hello Heating Help experts-- I hope you don't mind if I beg for some wisdom...---We have a residential customer with a steam boiler in the basement- the 2nd floor is served by steam radiators, the 1st floor is served by a water baseboard loop (the baseboard loop does include 2 cast iron radiators recessed into the wall).
The main complaint is not enough heat from the first floor baseboard zone. When testing the baseboard loop I am measuring 177 degree supply water going out to the baseboards and 123 degree returning from the baseboard loop.
There are other obvious problems we can see with the baseboard loop---the baseboards are obstructed by much clutter and some covers are missing, there are some sources of outside air coming in through window a/c, and windows with problems--but I want to make sure our boiler and the loop set-up are doing all that they can.

First Question: Does the 54 degree temperature drop across the baseboard loop suggest to you that we do not have enough gpm travelling through the zone? Since the baseboards are so obstructed I was expecting to see a smaller temperature drop (less than 20) but instead we have a much larger drop than expected. Each baseboard feel "warm" so I hink we are getting some flow but maybe not enough. When I throttle a ball valve closed and open again with my ear against the valve I can hear some flow but of course I cant tell how much.

Second Question: If we have low gpm, how likely is it for it to be caused by debris/corrosion within the piping? These baseboard loop zones on steam boilers are not exactly common for us but I havent had any experience with them "clogging up" either---is this a common thing and can it be cleared with chemicals?

Some more info:
The circulator is a stainless steel cartridge type.
There is an aquastat wired in to cycle the burner off before the water gets to steaming temperature.
A 2-pole relay is used to activate the circ pump on a call for heat using 1 set of n.o. contacts to turn on the circ pump and another n.o. to close the TT thermostat connections on the boiler (but the aquastat mentioned above will break the TT circuit when needed).
There is a by-pass tee to prevent baseboard zone from getting steam into it, but it actually has been closed since the baseboard complaints have started.
The baseboard zone is larger than I am used to seeing with these type of set-ups---there is about 50' of copper fin tube, plus (2) recessed wall radiators- estimated 20sqft edr for each of the 2 radiators.

Any advice would be appreciated.
Thank You.
Ron R

Jamie Hall

You don't have anything like enough flow. It could be that there is clogging in the pipes -- it could also be that you simply don't have enough pump in there. Further, if all that radiation is piped in series, the units at the end of the line are going to get cooler water and may not heat well.

kenlmad

My tayco cast iron 007 that pumps a hot water loop off my steamer to my basement's 20' of baseboard got jammed with rust during my first heating season. I don't know if it is common nor do I know if chemicals can fix it ( I doubt it).

My pump was installed incorrectly by the plumber with the motor can vertical and downward from the pump. The canned cartridge rotor was clogged with rust and slowing down the pump or jamming it completely. My attempts at rinsing out all the trapped rust through the small weep hole on the motor cartridge were futile.

I ended up replacing the pump and rotated the mounting flanges 90 degrees so the motor is in the manufacturer's specified horizontal orientation. It has not had a pumping problem since then.

Ron R

Thanks for the reply Br. Jamie---looks like we have some more digging to do. Will get back to the site and take some things apart to check further.

Ron R

Kenlmad---I'm worried about the cartridge type pump we used (like yours it's a 007, but in stainless steel).
It's installed horizontally like it's supposed to be but maybe the small passageways inside are just more likely to get blocked up. We'll go back there and bring a 3-piece series 100 booster pump in case the small taco is getting jammed up. Thanks for the reply.