Central Heating A Retrospective
Central Heating - a retrospective. - UPDATED
A second epic battle with my heating system - The Airlock strikes Back! I’ve updated my methods for v2 of the battle.
After I thought all was lost, a couple of days and the air shifted. Aside from a hose quite a few other things happened along the way. What went well….
Attaching a hose to the top of a radiator worked well though buying a correct attachment (15mm for me) would have been less messy. (Second time around I bought a 15mm garden tap and screwed it into the radiator and then hoselocked the hose onto the tap, this was far far less messy as long as the other end of the hose didn’t have a non-return hoselock on it!)
Also put a towel over the hand that is shoving the hose in to prevent everything spraying everywhere! We had an interpart 6m head pressure pump that was only registering a flow of 10 when on max, after shifting the airlock it measured 45 which I’m assuming is fairly normal not that there’s a manual on the internet. Having drained half the system (the upstairs) by letting it flow out of the top of a downstairs radiator, I blead all the rads and refilled the system. It worked at 45 for 5 mins before it dropped back to 11 - classic airlock I thought. But given that the boiler and filter (MagnaClean) had been in a massive ‘U’ bend their part still had the water in it when I drained the system, so I figured I could rule them out as not being the problem given it worked for the first 5 min. It was the return side of the pump
If your getting air out of the flow side of the pump, unscrewing it a bit with a bucket underneath works well. Turn pump on max and then kill the power seems to help push the air out. Rinse and repeat.
If when you thump your pump it magically starts working it’s not a good pump! These interpart pumps with a flow gauge on them provide additional insight into what is quite an opaque system.
When both values are turned off (0 for the thermostat), once you have opened up the bleed value water should fairly quickly stop coming out of it - this indicates both values work well closed. By opening up one value and leaving the other closed you should get water coming out of the bleed hole - this shows not only that the values can be closed but thst they also can be open. (We had dodgy taps under our towel radiator that only had an off position. Drained system and swapped out the taps - unscrewed innards and replaced - thankyou screwfix.)
With both values off and the pressure off from the bleed, retigten the bleed and unscrew the radiator, flip it and put fingers in the holes (large double radiators are heavy- watch your back). You can now use a garden hose on it to flush out any bad bits. When you putnit back open the flow value first and bleed the air out before opening the return.
What could have gone better….
Bleed valves are not just on radiators- a towel radiator also has one, the non-digital pumps with the large screw in the middle- thats a bleed value also. And magnacleans have bleed values at the top also. If you don’t have one where you need it you could just unscrew slightly a compression joint.
|Due to building regs our system is fitted with an auto release value that returned the hot water from the boiler to the bouler if it was too hard to go round the rest of the system. 1 means 0.1 bar pressure before it opens, 6 means 0.6 bar pressure before it opens. For a long while I was assuming turning it down would reduce the flow but it is counterintuitive. Helps when you know what the numbers mean!|