Hydronic Heating / mono-flow

Steve Smrecek

Dear Dan:

About 6 years ago you came to my rescue with a simple soulution on a mono-flow system. I am an alumni of your heating seminars and have been "pumping away" for eighteen years.

I recently replaced a leaking steel hot water boiler witch had a split loop (1-1/4" black steel piping). After startup, bled out the radiation which consisted of mostly small commercial type fin tube baseboard and 2 semi-recessed convectors. My customer had told me prior to starting the job that the second floor convector did not work and that other contractors has tried numerous things to get it to heat.

I found the first floor bathroom convetor not getting circulation after the air bleed. I questioned the fact that there was a taco # 110 circulator on the original boiler and I had used a taco # 007. I spoke with the Emerson-Swan-Taco rep and he told me to try a # 0010. I tried this circulator and found no change.

Two days later I returned to the job and installed gate valve between the supply and return tees to change the pressure to the branch. Naturally I had to bleed the system again and found that very convector heating without restricting the the flow of the main line. I also found a section of baseboard which was heating just fine on the first round not getting ciculation. Its seems that whatever the restriction is is has moved in the system. Do ou have any ideas on this???

heatguy

Steve, if i remember correctly with a monoflo system if you dont have flow through sections of radiation it will effect flow through other sections and kind of float around as the pressure drop lets the air out and locks out sections of radiation. i would check your air elimination device

EJ hoffman

bleed bleed bleed

If you can shut off all the radiators except one. It is best 2 start with the lowest and closest to the boiler. then move on up the line. It is best to turn off as many sections as you can and allow the pump to keep pusshing the air and water while you bleed the system. I like a purge tank for this but most of these systems don't have purge tees cut in. while you are bleeding check all over for signs of leaking especially packing nuts, remember a leak will intrduce more air into your system. Size your pump look in the library the B&G sizing chart and rules of thumb will really help you, don't just throw pumps at the system. Go back 2 days later and bleed again. Heating all that fresh water will introduce more oxygen heavy water that will be released after it is heated, and if you don't have a air seperator you will get more air locks

Eric_20

Open that gate valve! you have air stuck in one of the monoflow baffeles. You probabley have just a 1/8" purge up near the radiator, just install a 1/8" nipple and a 1/8" x 1/2" coupling then a draw off, then purge the heck out of it. Shut off the feeder and relieve the pressure but don't drain it! Just put the 1/8" valve back in and you should be good to go. One time I had to install two ball valves and a draw off on the run outs to the effected radiator. Good luck, I hate having to drain those monoflow systems.

Unknown

Mono-Flows are fun,

I have that system,,, if you have an air-scoop, enough pump, properly located then you should be able to purge any air. Mine is CIBB, 2 story(zoned), and I very seldom(if ever), bleed the system at the rads when I drain-it.

Dave