Coalpail.com Forum

I started renovating a room in my house with fin tube radiation. I also have an indirect hot water tank so my boiler heats both my perimeter radiation and domestic water in my storage tank. I have 2 flow control valves on my boiler, one for my perimeter heat and one for my domestic hot water. I tried to shut the valve feeding the perimeter heat but the small handle on top just kept turning and wouldn't stop, so obviously this wasn't going to work. I shut the supply water going into my boiler. I cut out the fin tubing in the room I am renovating. All was good, so I thought. I noticed the circulator pump for the hot water storage tank was constantly running and was VERY hot! It also sounded like it was air bound at times and I lost my hot water. I opened the boiler drain on the return line into my boiler to bleed the air but nothing came out, in fact it was pulling a vacuum. The boiler wasn't firing off either. I finally capped the feed into the room and turned the boiler water feed back on. Everything works fine now. I'm confused as to why I needed the feed water into the boiler on for the hot water tank loop to work properly. Maybe by cutting out the perimeter radiation the system got air bound?

You figured it out. When you cut the system and took out the fin tube rads you got air in the system. The system not being pressurized couldn't force the air out. When you opened the water back to the boiler you pressured the system pushing the air along with the water until you could get it out. The pump moves water, it doesn't provide pressure.

No harm, no foul, now you know.

Congrats for a job well done!

Thanks. I called my oil company last night since I have a maintenance contract with them, I was scheduled for first thing today. I was thinking about it while laying in bed and it hit me. Fixed it and canceled my appointment. Although, I should have them replace the faulty flow control valve since it doesn't shut!

That is why I put in purge stations in all zones on my Buderus oil fired system 10 years ago. With a purge station you just shut one valve, and put a hose on the purge station and house pressure at the fill valve pushes all the air out. When there is no more air the water is a perfect stream. The air scoop handles the rest.