Sorry to post a non Bay question but think I may be about to be given the run around by someone I've employed to repair and power flush my central heating system and could do with expert advice. System power flushed yesterday. (It's an old system - Ideal Mexico boiler, pumped, sealed system with hot water cylinder in the airing cupboard). Last night the hot water from the hot water cylinder turned brown when a bath was drawn. It was clear before the power flush so my thinking is the power flush has ruptured the coil inside the cylinder and the remnants from the crud that was in the system is bleeding into the hot water coming out of the taps. What do you think? Thanks.
Also if the hot water is open vented but the heating is sealed, if the coil is gone then you sometimes get discharging from the cold water storage tank overflow if the mains water pressure is good enough. What happens is the mains pushes into the cylinder via the knackerd coil. This causes the extra water to rise up the cylinder vent pipe until it runs over into the cold water storage tank. This raises the level in the tank to the overflow level. However if you draw water off then obviously this lowers the level in the tank. So leave the system to stand for a few hours without draw off. Also check to see if the level in the tank is higher than the normal water mark or higher on the ball valve float. Basically if the heating system is pressurised, over time the greater pressure in the heating 1-1.5 bar over atmospheric bleeds into the open vented cylinder side, you top up the pressure via the fill loop and it just bleeds into the dhw side again. Thus increasing the the water level in the tank over time You could try getting your man to top the system pressure to about 2 bar and see if it holds. If it doesn't then that's another good indication that something's up with the cylinder. This can also happen on open vented systems when the coil goes, the greater head of dhw pushes into the ch side and causes the header tank overflow to run. This ones normally more obvious as it doesn't require you to replace the system water via a fill loop. But from your description it's a fecked cylinder.
To be fair to your guy, there's always a risk when powerflushing. So much of the system is hidden from view. There's no way for him to know that the cylinder coil was on its way out, and if you system was having enough issues to require a flush then there's no a great deal of other options but to flush it. I've had rads go after a chemical flush, my mate had a pipe under a suspended floor go when he ran his machine. Power flushes can sometime cause more aggro than they fix.
Cheers Rustbucket. The hot water is open vented I think. I'll have a look see in the loft and check the level of the cold water storage tank. I chose him because, although not the cheapest, he did suggest a solution (changing it to a sealed system) to stop the open system from continually running into the F&E (?) tank and causing radiators to fail. I would have preferred a low pressure, high volume flush over a couple of days offered by one of the other guys. There's just the question of one rad not turned on (TRV head lying on the floor) and a large cold spot on one of the other rads... As a matter of interest who picked up the tab when a radiator burst during power flushing?
Customer paid for the rad as it was really old. I fitted it foc If your system is pumping over then you have one of two issues. Either the water pump is in the wrong place on the pipework or more likely there's a partial blockage, normally in the h arrangement or air separator if u have one. Has anyone tried a magnet on the area around the cold feed?
Also just get them to check that the control stat on the boiler is actually shutting off at the correct temp by clipping fga sensor to the flow pipe. I went to a breakdown last winter. At a big house. The customer constantly had air in the system. The previous company said it had to be flushed and charged him about £1500. When that didn't work they told him he needed floors up and the upstairs re piping. He panicked and asked around and somehow got my number. Anyway I fixed it with a £30 boiler stat. It wasn't pumping over as they suggested it was boiling over due to stat fault. Muppets.
Got here a bit late ,lots of sound advice been posted already .If you really want the 100 pc certain confirmation that the coil has given up the ghost ,drain the heating system and remove the flow and return connections at the cylinder and blow in one end ,check that it comes the other end and a there is no leakage from the domestic side off the cylinder ,which would be evident by water leaking from the open ended coil connection
I've had the heat exchanger in a boiler leak when power flushing and various rads .It's a laugh a minute my job
= No no one has tried a magnet around the cold feed - presumably if it sticks to the copper pipe there's a load of rust inside it? (Bit like a using a fridge magnet to test for filler on a Bay?!) Thanks for all the help, I really appreciate it. Have been in touch with the plumber. He's suggested that as he had to replace pipework to the cold water header tank in the loft, there could be remnants of crud from that still in the system and to run the hot water. I've emptied the tank, left the water running and it has improved the discolouration (still noticeable) but suspect the test will be once the boiler fires up tonight and the system is put under pressure. He asked if I could replace the TRV head and open the lock shield valve as it seems that radiator was forgotten about - just hope it was forgotten to be flushed... The rad with the cold spot should clear after a 'couple of weeks', is that professional jargon for the crud that's in there may move around the rest of the system and the rad operate properly or am I being conned do you think?
Why would he have altered the pipework supplying the dhw if all he was doing was sealing up the heating? If a system has been flushed how can there be a cold spot. Cold spots are caused by blockages in the rad. Each rad should be flushed individually on a normal two pipe system so that's an odd statement.
Yes the magnet on the h in the airing cupboard is a good little trick to find blockages. Basically copper as you know isn't magnetic but sludge comes from the oxidisation of the radiators which are steel, so blockages are often magnetic. Only in very bad cases will the magnet stick and hold, but if you place it where you suspect the blockages are you will feel resistance when you lift it off. Especially when compared to a pipe you know to be clean.
For loads of useful info check out plumber parts.co.uk on YouTube. That guy explains stuff really well and it's not too technical. Although on forums I make out I'm a heating engineer. I'm actually an ice cream salesman. I just repeat the stuff from his videos to make myself sound more important. You want a flake in that love?
Get him to take of the cold rad and flush in the garden with a hose,both directions and take out the vent and blank plug.turn it over with water in it and tap it with a rubber mallet
- thanks I thought so too. I was told each rad was flushed separately as you say but other than standing over someone and watching it happen, not possible to check. There were 13 rads, he started upstairs (which were not as bad) and worked downwards to the worse ones. He started just before 9am and finished at 3.45pm.
Yes that's my thinking now as that's what he did with the radiator he took off to use to flush the system. Again thanks for all the help, feel a lot clearer in my own mind now what is needed to be said/done to get it sorted.
