07-11-2016, 09:01 AM
Last month I finally got round to cleaning out the system. I fitted a temporary contraption of valves to alllow forward and back flushing. Then put Fernox DS40 in the system. At first I had trouble getting any circulation - it must have dislodged a lot of black gunge. Then it alll settled down and I ran the system gently warm for 3 days. Added more DS40 as I wasn't satisfied that it was 100% clean. After neutralising the DS40 with the sodium metaborate sachets I forward and back flushed each rad with mains pressure for at least 5 minutes. Added Sentinel X100 and refilled.
Lots of bleeding later the system was running nicely. Let it settle for a few days to let the dissolved air out of solution, bled again and set the cold pressure to 1 bar. To my astonishment the cold pressure rose to almost 2 bar over the next few days. I though the filler loop might be letting through but it wasn't and I left it disconnected. Then I thought about leakage from the DHW secondary. Not possible because the head is only about 18 feet, so the secondary pressure is only about 0.5 bar. Although I've got a minor doubt about gauge pressure and absolute pressure. The only other thing I can think of is that something chemical is going on. Which it shouldn't because there's ample X100 in there.
I let it run for a couple of weeks like this. Bled again and not too much air came out. Set cold pressure to 1 bar. After a few days the cold pressure is up to 1.2 bar.
I'm a bit confused and worried. I think I'll take a sample of water and put it in a closed jar with some nails, just to prove the chemistry is OK. Or get one of these test kits: http://www.plumbase.co.uk/sentinel-x100-...-0-2205364
Lots of bleeding later the system was running nicely. Let it settle for a few days to let the dissolved air out of solution, bled again and set the cold pressure to 1 bar. To my astonishment the cold pressure rose to almost 2 bar over the next few days. I though the filler loop might be letting through but it wasn't and I left it disconnected. Then I thought about leakage from the DHW secondary. Not possible because the head is only about 18 feet, so the secondary pressure is only about 0.5 bar. Although I've got a minor doubt about gauge pressure and absolute pressure. The only other thing I can think of is that something chemical is going on. Which it shouldn't because there's ample X100 in there.
I let it run for a couple of weeks like this. Bled again and not too much air came out. Set cold pressure to 1 bar. After a few days the cold pressure is up to 1.2 bar.
I'm a bit confused and worried. I think I'll take a sample of water and put it in a closed jar with some nails, just to prove the chemistry is OK. Or get one of these test kits: http://www.plumbase.co.uk/sentinel-x100-...-0-2205364
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
