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- 10 Nov 2014
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I’m at my wits end and looking for advice – this is a long one as it’s been going on for almost a twelve month now, so bear with me (I'm including it all in case some is relevant).
System is a Glow Worm boiler 38hxi fitted downstairs, with Megaflow HW Tank in an airing cupboard and F&E tank in the attic.
View media item 86035
New rads (17 in total with TRV's) put in at the start of the year but the property had been empty before that so I’d never seen it up and running (had all been drained down). Nothing else was altered at that time.
The initial problem was that the boiler would come on but would then cut out intermittently. Neither could we have the HW and CH on at same time. The boiler was serviced and found to be working okay. The Port Valves were replaced and that fixed the problem of not having CH and HW at same time, but the boiler was still cutting out. If it did miraculously stay on, some rads would not warm up and setting the boiler at anything from 72 degrees to 82 degrees (the max) would cause kettling.
A check showed the system was very dirty and full of magnetite, so it was drained down and power flushed by a friend (he works for British Gas and was helping me out). The system was reinstated and seemed to work, but it was done in the height of summer time so then it wasn’t put on for two weeks. When I tried it again, it was back to cutting out.
Thinking it might actually be the boiler I approached Glow Worm who sent a Group Service engineer out. He said it’s not a problem with the boiler and it was working fine – he concluded the system is too restrictive and had too much 22mm going into 15mm pipework (but did not lift a single board to determine this – all he did was look at the pipes going out of the boiler). He stated I’d have to re-pipe the whole system to sort it out, but as a possible fix he turned down boiler from 38kw to 30kw output to alter the heat curve the boiler would be looking for. This fixed the boiler cutting out but the system then struggled to warm up - one radiator in front room still refused to warm up at all.
Because of this I suspected the pump might be operating at less power than it should (it had been disassembled and cleaned out during powerflush) so it was replaced with a like for like (Grundfos 50-60). This made no difference but the system is now really noisy around the pump and immediate pipework. When it starts to warm up there's lots of fizzing and whooshing which sounds like a lot of air in system and can hear air bubbling though some rads (constantly having to bleed upstairs bathroom rad and the bedroom rad at the end of the run). Once again I found we couldn’t have HW and CH on at same time.
I then suspected the noise and air could be caused by a block in cold feed from tank and that bleeding the rads was actually lowering the water level in the system without it being replenished. A check of F&E tank showed it was full of sludge and magnetite. The tank was also very full of water, but had not overflowed. I drained the tank down and cleaned it out before checking for a block in the cold feed - the tank refilled fine when water was drained out of a radiator indicating no blockage. However, a check of pipework around the flow and return in the airing cupboard with a magnet indicated some slight sticking (but only slight and no real adhesion – I could brush the magnet off the pipe rather than needing to apply any real force).
The friend who Powerflushed was called back in desperation. He could not remember if he has cleaned out the tank when powerflushed (I suspect he didn’t). The new issue of HW and CH not being on at the same time was resolved by replacing the external timer control panel to the boiler. He maintains the pipework can still be slightly magnetised even if there is a thin film of material on the pipe and not necessarily a blockage or restriction. He says the system noise will eventually go and to use something like Fernox boiler silencer to stop it quicker. He's looked at the pipework under some lifted boards and can't see that it would be restrictive.
I thought this was all going to be okay until I’ve gone into the attic this week and found the F&E tank is full of tepid, murky water (but not black and there's no sludge or magnetite). There’s lots of condensation in tank (and it also seems to be causing condensation in the attic in this cold weather). The noise around the pump is worse than ever.
I understand this indicates it is possibly pumping over (and the vent pipe is red hot after a while indicating it is forcing hot water up the pipework into the tank). The Rad in the front room still refuses to get warm until at least two or three of the other rad TRV’s have shut off. The pump was set to two, so I turned the pump down to its lowest setting but then the boiler keeps cutting out as the flow is not strong enough to support the heat curve it’s looking for.
I’m at a loss as to what to do next – I’ve gone through four different tradesmen / people now in trying to sort this and it’s costing me an arm and a leg to try and get it working right.
Can anyone give me any advice on what’s going on? Could it be the pipework is actually too restrictive? The usage of the premises before I owned it indicates they would never have allowed it to be cold there (it was a respite home for the vulnerable) so of all the things there that would needed to have been right it would have to be the heating and a botched installation is hard to believe.
System is a Glow Worm boiler 38hxi fitted downstairs, with Megaflow HW Tank in an airing cupboard and F&E tank in the attic.
View media item 86035
New rads (17 in total with TRV's) put in at the start of the year but the property had been empty before that so I’d never seen it up and running (had all been drained down). Nothing else was altered at that time.
The initial problem was that the boiler would come on but would then cut out intermittently. Neither could we have the HW and CH on at same time. The boiler was serviced and found to be working okay. The Port Valves were replaced and that fixed the problem of not having CH and HW at same time, but the boiler was still cutting out. If it did miraculously stay on, some rads would not warm up and setting the boiler at anything from 72 degrees to 82 degrees (the max) would cause kettling.
A check showed the system was very dirty and full of magnetite, so it was drained down and power flushed by a friend (he works for British Gas and was helping me out). The system was reinstated and seemed to work, but it was done in the height of summer time so then it wasn’t put on for two weeks. When I tried it again, it was back to cutting out.
Thinking it might actually be the boiler I approached Glow Worm who sent a Group Service engineer out. He said it’s not a problem with the boiler and it was working fine – he concluded the system is too restrictive and had too much 22mm going into 15mm pipework (but did not lift a single board to determine this – all he did was look at the pipes going out of the boiler). He stated I’d have to re-pipe the whole system to sort it out, but as a possible fix he turned down boiler from 38kw to 30kw output to alter the heat curve the boiler would be looking for. This fixed the boiler cutting out but the system then struggled to warm up - one radiator in front room still refused to warm up at all.
Because of this I suspected the pump might be operating at less power than it should (it had been disassembled and cleaned out during powerflush) so it was replaced with a like for like (Grundfos 50-60). This made no difference but the system is now really noisy around the pump and immediate pipework. When it starts to warm up there's lots of fizzing and whooshing which sounds like a lot of air in system and can hear air bubbling though some rads (constantly having to bleed upstairs bathroom rad and the bedroom rad at the end of the run). Once again I found we couldn’t have HW and CH on at same time.
I then suspected the noise and air could be caused by a block in cold feed from tank and that bleeding the rads was actually lowering the water level in the system without it being replenished. A check of F&E tank showed it was full of sludge and magnetite. The tank was also very full of water, but had not overflowed. I drained the tank down and cleaned it out before checking for a block in the cold feed - the tank refilled fine when water was drained out of a radiator indicating no blockage. However, a check of pipework around the flow and return in the airing cupboard with a magnet indicated some slight sticking (but only slight and no real adhesion – I could brush the magnet off the pipe rather than needing to apply any real force).
The friend who Powerflushed was called back in desperation. He could not remember if he has cleaned out the tank when powerflushed (I suspect he didn’t). The new issue of HW and CH not being on at the same time was resolved by replacing the external timer control panel to the boiler. He maintains the pipework can still be slightly magnetised even if there is a thin film of material on the pipe and not necessarily a blockage or restriction. He says the system noise will eventually go and to use something like Fernox boiler silencer to stop it quicker. He's looked at the pipework under some lifted boards and can't see that it would be restrictive.
I thought this was all going to be okay until I’ve gone into the attic this week and found the F&E tank is full of tepid, murky water (but not black and there's no sludge or magnetite). There’s lots of condensation in tank (and it also seems to be causing condensation in the attic in this cold weather). The noise around the pump is worse than ever.
I understand this indicates it is possibly pumping over (and the vent pipe is red hot after a while indicating it is forcing hot water up the pipework into the tank). The Rad in the front room still refuses to get warm until at least two or three of the other rad TRV’s have shut off. The pump was set to two, so I turned the pump down to its lowest setting but then the boiler keeps cutting out as the flow is not strong enough to support the heat curve it’s looking for.
I’m at a loss as to what to do next – I’ve gone through four different tradesmen / people now in trying to sort this and it’s costing me an arm and a leg to try and get it working right.
Can anyone give me any advice on what’s going on? Could it be the pipework is actually too restrictive? The usage of the premises before I owned it indicates they would never have allowed it to be cold there (it was a respite home for the vulnerable) so of all the things there that would needed to have been right it would have to be the heating and a botched installation is hard to believe.
