I have recently started up a radiant floor heating system in my shop. It ran for 5 days and everything looked good. Since my shop isnt totally insulated yet I realized that i was really wasting propane. Yesterday I added antifreeze to the system and decided to “idle” the water heater on vacation mode. I was holding about 20 to 18 lbs of pressure. Tonight when I came home from work I noticed the pressure guage only had 1 or 2 lbs. I heard gurgeling in the pipes around the pump, I then turned the grunfos pump to the #2 setting…. well air and water was coming out of the air scrubber and the water heater had alot of gurgeling going on in it. All three loops of tubing also had air in them something that im fairly sure wasnt there after adding antifreeze. Any ideas on the pressure loss and where all this air is coming from would be greatly appreciated. I
know there will be pressure drop due to a cooler h2o temp but 20lbs??
Replies
It often takes days and sometimes weeks to get the air out. Sometimes it will seem like you have the air out and then there is more. You have one thing making it harder for you but it's just the nature of the beast. In-floor heating is harder to purge because of the loop lengths and the flow rate. The tubes are usually 200 to 250 ft long and only1/2" dia. If a plumber did that to a faucet we'd call him a hack. Second, the water is moving pretty slow to facilitate heat transfer to the floor from the water. I've had the best luck by valving off all of the loops but one, isolating the heat source with it's relief, turning up the pressure and pumping through one loop at a time for an hour or two each loop. After you go through each loop several times don't forget to bleed pressure back out of the system before opening the valves back up to the heater, glycol makes a mess DAMHIKT. This is the part of the job that allows you to enjoy the proper beverage in a little peace and quiet. gotta use the "right" beverage because the potential for impatience and frustration is high, and patience is what is needed. Good luck and enjoy the day. :^)
Chris
But what about the water coming out of the air valve? could that be defective? I have never had any moisture exit my air valve. Could he have it installed wrong? The air vent pointing up, not down or sideways.
thanks for the reply. the air eliminator is a honeywell unit with a pressure tank attached to the bottom, precharged at 12 psi. before putting the glycol in everything seemed to run well. i have isolated each loop to purge the air but didnt think that i was pumping that much air into the system when i filled with antifreeze. apparently alot more entered than i anticipated. when the whole system is cold say in the low 40's what pressure should i see on the pressure guage? currently i dont have any pressure, when the system was running it held 18 to 20lbs. @ 125 degrees. this is also a closed system. thanks.
I'm not sure what your pressure should be . Mine is tied into the well with a backflow prevent valve so mine is at 50psi.
Your pump will make some pressure but it depends on the valve settings and friction .
An autofill valve is actually just a regulator with a relief and check. This regulator is pre-set from the factory at 12 psi. It is field adjustable, just follow the little instruction book that came in the box. What this means is that the regulator will try to achieve 12 psi minimum no matter what the temp. The check valve keeps the water in the system that was in there when it was cool from leaving when it heats up causing the pressure to rise. So if your system sees 40* then it will be 12 psi there and rise with the temp. For now I would keep the pressure up because higher pressure helps get the air out by squeezing the microbubbles into bigger bubbles and out the vents faster. Use the fastfill lever on your fill valve to bypass the regulator and raise the pressure beyond 12 psi. The system relief should be 30 psi so stay under that. Later you need to remember to lower the pressure after all of the air is out. Lower pressures help keep the microbubbles in suspension until the air separator can catch them. Good Luck
Chris
The other post is on top of the problem , more than likely when you added anti-freeze you didn't bleed the lines completely. Water heater; are you talking about a heater hooked to the domestic system? if so you need back-flow proctection any time you put anti-freeze in the system. Air vent; if you are getting more than a few drops of water out of it, its probably defective. Hope this helps.