intermitant hot water

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intermitant hot water

Post  markymark on Sat Apr 20, 2013 5:53 am

Hi, hot water varies in temp and have replaced hnw and other in pipe sensor. Exchanger replaced 9 months ago. Any ideas? Thanks

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Re: intermitant hot water

Post  scorp on Sat Apr 20, 2013 1:35 pm

Any errors on PCB display?
Worth to check HW pump.
Search for similar fault on the forum

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Re: intermitant hot water

Post  markymark on Sat Apr 20, 2013 11:29 pm

Thanks for your reply. I have checked the PCB readings and all seem to be near what others have posted. When hot water is run the PCB changes status, but seems to cut the pump in and out, which is why I thought it was the sensor. When I replaced the hnw it was all corroded, so thought that was problem solved, but problem persisted. Them I changed the other in pipe sensor, that looked ok actually and problem still persists. How do I check the he pump? I think I do have a spare I could swop out. I've drained the system down before as have changed the heat exchanger.

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Re: intermitant hot water

Post  markymark on Sun Apr 21, 2013 1:05 am

I thought I'd run a test to see what readings I got. When hot water tap run the led display goes from middle bar of the 8 to both middle and bottom lines. Bottom lines stays illuminates for 30/40 secs, that I take it is instruction to run hnw pump? Bottom bar then goes out for a few seconds, then re illuminates, which I assume is the PCB switching the pump in and out which would explain the fluctuations in hot water delivery. If the new sensor is working correctly, then is it down to a faulty PCB? The cost of these new is £250 plus vat, so really want to make sure this is the fault before spending this much. I take it reconditioned ones are available? Anyone got any idea for solution as a. Getting bored of having to jump in and out of shower flow and my wife likes her hot baths!

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Re: intermitant hot water

Post  scorp on Sun Apr 21, 2013 4:07 am

As far as I understand the system, when HW running, temperature drops and PCB starts pump and regulates its speed supplying around 80V-150V depending on the flow. When HW flow stopped, PCB keeps pump running for about 30 seconds. It makes me feel that either sensor is faulty or PCB. It is very small chance that your new sensor is faulty(or got faulty during installation) because you don't have any errors and you most likely don't see any interruption of the HW temperature on the display when water is running. Then the only part left is the PCB. I would recommend trying to fix it by replacing caps. It costs no more that £6-£7 and half an hour soldering job. Check my posts.

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Re: intermitant hot water

Post  scorp on Sun Apr 21, 2013 4:29 am

In order to check the pump it will be enough to check voltage on it in the range I mentioned and make sure it is rotating. You will need to unscrew big cap in the middle(expect some water from there). As for replacing it, keep in mind that HW pump is not the same as others on the system. It support speed regulation but others only can run at constant speed

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Re: intermitant hot water

Post  markymark on Sat Apr 27, 2013 1:48 am

I replaced the hnw switch, just to check it wasn't faulty, but made no difference and have run out if ideas now. Anyone know where I can get a reconditioned acb? Think it worthwhile replacing pump to rule this out?

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Re: intermitant hot water

Post  markymark on Fri Aug 02, 2013 12:38 am

And so the saga continues. I replaced the caps, which seemed to make the problem worse, which may be down to my soldering skills, so decided to bite the bullet and replace the PCB, with a reconditioned part, but low and behold problem persists! Anyone any ideas? I've already replaced hnw sensor and tried a 2nd to make sure that wasn't at fault. Still have the led coming on and off at intervals, but is this normal. I have a spare switch that I will replace, but if that doesn't work then the only thing left is the pump. Anyone know the correct one to get as I seem to remember they all look the same, but from previous comments the hnw is different as it runs at variable speeds.
Thanks in advance, Mark

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Re: intermitant hot water

Post  mike on Wed Aug 07, 2013 5:35 pm

XB 004 is the pump.
Must be that one for the DHW
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Re: intermitant hot water

Post  markymark on Wed Sep 18, 2013 5:47 am

I have not yet changed the pump, but did see on another thread that the HE can cause the pump to cut in and out due limescale but as this has been in less than a yr I think unlikely and we also get good hot water pressure. Now weather is getting colder the swing in temp is getting wider and more uncomfortable. About to throw in the towel and get a pro in to solve! Anyone any ideas?

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Re: intermitant hot water

Post  markymark on Wed Sep 18, 2013 6:20 am

on previous chat scorp said that the HW pump is different but I've checked all three and they look identical? They are grindfos type: UPS 15-50X18. Do they look the same as the XB 004. the pumps have not been changed previously?

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Re: intermitant hot water

Post  markymark on Wed Sep 18, 2013 9:57 am

I decides to order the xb 004 pump as this is the only componant that I haven't changed. The system has the switch facility and I remember running a bath last week with it on the he setting and the water from the two still varied in temp? I've now read the instalation guide and it states that when in this setting the she pump should run at full speed. If it doesn't Then I assume it would effect the variance of the hot water at the tap, so hopefully this I indicates that the dhw pump has been at fault all along and has been an expensive excercise in fixing! I'll let you know what happens once I install the new pump. I notice that there are valves either side of pump. Is it sufficient to close these to take out the pump or would I be advised to drain the system down completely?

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Re: intermitant hot water

Post  markymark on Thu Sep 19, 2013 11:37 am

Well and so the saga continues.. New pump arrived today from keep the heat on, only ordered yesterday at 3pm. Pump fitted and low and behold intermittent hot water issue persist! I also checked the check valve below the she pump whilst it was out and was free and working ok. I've now changed the acp, both sensors and the dhw pump. Might as well and go and buy a whole new she. Anyone know what the problem might be? I changed the phe less than a yr ago, and hot water pressure is still really good so can't see that this would be causing the problem. Any one know of a good heating engineer near buy st Edmunds?
Thanks, mark

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Re: intermitant hot water

Post  mike on Thu Sep 19, 2013 1:36 pm

Hi Mark,
Never gave it a thought.
Bury St Edmunds!
Very hard water indeed.
I had to change 8 PHE's in Bury St Edmunds not long ago.
Only a year old.
And if those people do not fit a water softener, they will need one every 12 months.
Mike

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Re: intermitant hot water

Post  markymark on Fri Sep 20, 2013 1:22 am

Hi Mike, thanks for your reply.
I'm on my 3rd PHE in 8yrs but previously the hot water pressure gradually dropped over time, so I knew it was scaling up but it is still very good. Is there anyway to descale them effectively or is replacement the best option always? the intermitant water has improved slightly today, but I'm putting that down to my optimism and also the new pumps performance. I've spent over £250 on parts and still not sorted problem. Looks like I'll need to shell out another £90 on a new PHE?
What's the best type of water softener to fit. I have a 3 story town house, 3 of us, three toilets, 2 showers and a bath. Any idea of cost for one and instalation? Do you do them?
Thanks again, Mark

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Re: intermitant hot water

Post  markymark on Fri Oct 18, 2013 1:17 am

Well after months of head scratching I have finally sorted the problem. After previuosly replacing both sensors, the PCB, dhw pump I fitted a new heat exchanger yesterday and full power consistant hot water has been restored hurrah! I had not fully considered it to be at fault as I still had fairly good hot water pressure. When I took the old one out there was a significant build up of limescale on the pipes feeding the phe and a few big lumps present in the pipe as well. I guess the hardwater has done some major clogging of pipes so it is only a mater of time before it causes further problems and I will need a new system. When it does go it won't be a boilermate system and will also invest in a good water softner system! As I've drain the system should I be adding/added some additive to the storage water? I've spent circa £300 on parts but reakon it would have cost me a lit more to get someone out to sort it. On the matter of water softners is there any economic system device I can fit/install to help with the hard water. I've looked at full systems and good ones are around £700 and i know that they can help recover systems but will one be able to reverse ten years of build up on internal pipes?
Hope my blog has helped someone!
Mark

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