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Advice on replacement heating system...

Discussion in 'Plumbing and Central Heating' started by heavysoul, 5 Jan 2019.

  1. heavysoul

    heavysoul

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    Need some advice please as our hot water/heating system is 20 years old and we currently have an issue whereby radiators are coming on when the heating is OFF.

    I live in a 3 storey town houses built by Bovis around 1999. We still have the original Potterton Suprima 50 which is in the kitchen on the ground floor. We have a Boilermate 3 thermal store in an airing cupboard on the top floor.

    We have a British Gas Homecare contract and have the boiler service annually. We recently had the boiler PCB changed - first time in quite a few years. Others, the boiler seems OK (touch wood)!

    I have had BG out and the chap reckons the port valve is not closing properly. He changed the motor siting on top - but that hasn’t solved the problem. He was reluctant to change the port valve itself as it’s in a really awkward position with difficult access and said he couldn’t guarantee no damage would occur to other pipes etc - which would then cause further problems due to lack of spares available for the Boilermate.

    The recommendation was to look at changing the whole system “which would be far more efficient than what we currently have”. BG have since been round and have quoted just over £6,600 to change the boiler to a Valiant ecoTEC plus 418 Mk2 and also swap the thermal store unit for a Gledhill Unvented cylinder… add Hive Active Heating etc.

    All of my neighbours have had their systems replaced with Combi boilers (cheaper option - but the British Gas surveyor reckons we couldn’t have a Combi boiler set up due to it pressurising the system which would endanger buried pipework and increase the risk of leaks.

    Is he correct in saying that?

    He also said that the Combi boiler wouldn’t work with our showers (he referred to them as being pumped showers - but essentially you pull the control leaver up and move it left/right to adjust the mixed temperature). He said we would need combi compatible showers - although yet again, our neighbours are operating the same original showers with their combi boilers!

    Is he correct in saying that?

    Once we are out of the winter period, I will get a couple of local firms around to get advice and quote - but I would appreciate some views on options i.e. what would you do if it was you? I would ideally like to try and minimise any disruption e.g. needing to run new copper pipes that would be visible. The BG guy said this would be needed with the new system he was recommending.

    Is it worth getting another view on trying to get the port valve replaced? Would I have big problems if damage to other pipes did occur when trying the get the old port valve off?

    Is a new Combi system just not viable based on what the BG chap said?

    Could I not just swap out the Boilermate for a new thermal store? Why change to an unvented system?

    Any other suggestions welcomed…

    PS… apologies for long post - but I wanted to try and give all info.
     
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  3. Gledhill=nightmare...I would suggest unvented always rather than thermal store.
     
  4. oldbuffer

    oldbuffer

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    1. An unvented cylinder will operate at or above the pressure of a combi boiler on hot water. So risk of leaks on water pipes about the same.
    2. Its true that the central heating pipes would likely be under greater pressure with a combi boiler. However:
    2a. That's true for every conversion from open vented to combi or sealed.
    2b. You might get the odd leak, but unless the pipes are buried in screed, or you have laminate type floors everywhere, leaks can be fixed.
    2c. Sounds as if your neighbours have got away with it. Why should your property be different?
    3. Provided the showers aren't electric in any way (electric water heating or electric pumps) they will probably be fine.
    4. Re. the motorised valve:
    4a. Can't tell without seeing it, but even allowing for a little collateral damage and subsequent repair, likely to cost less than £500.
    4b. Did he do any electrical test to determine whether or not its the valve causing the problem? Likely to be the problem but might not be.
    4c. If its a modern Honeywell valve, you can take the entire head and valve works off, and replace, without disturbing the pipes.
    5. Its very unlikely a combi is not viable, provided you are prepared to put up with the limitations (only 1 hot outlet at a time unless a very big / storage combi).
    6. Your boiler is 20 years old:
    6a. Although its a good one (in my opinion), you probably need to start planning for a replacement in the next few years.
    6b. If you have to change the boiler, I'd suggest the combi route is the way to go, subject of course to on-site inspection.
    6c. An unvented cylinder is probably the best hot water alternative, but they are not cheap, require a mains pressure of around 2 bar with a flow no less than 20 litres per minute, installation requires a G3 registered engineer and has to be registered with the council (usually done by installer), they need an annual inspection, and require a pipe (minimum 22 mm diameter) to discharge any very hot water from a malfunction.
    6d. The thermal store solution is do-able, but there aren't many engineers really familiar with them. They can also have issues in hard water areas, although these can be mitigated / obviated with care.

    If it were me I'd go for the combi to start with and remove the thermal store, but not use the space. If necessary an unvented cylinder (or another thermal store) could be fitted at a later date and run off the combi, probably using the combi's direct hot water for the kitchen and the stored hot water for other rooms.

    I'd suggest your starting point is to get estimates for installing a combi and altering the system to suit from two or three local independents. You could perhaps ask your neighbours who did their conversions and what they thought of them.
     
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  5. heavysoul

    heavysoul

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    Wow... that's a really fantastic and comprehensive reply... thank you..

    Re the valve... I'm not sure what tests he did. He did do something to test the motor... which he changed even though he thought the one we had was OK. He just seemed really against being able to 'easily' remove the valve itself because of not being able to get at. He said that under the Homecare insurance we have that we'd have to sign to accept that some irreparable damage might occur that they would then have no liability if damage occurred and it couldn't be repaired!

    IMG_0086.jpeg

    The BG chap was concerned about the pipe on the right (above photo) of the valve saying it looked like it had been bent to make it fit - hence his reluctance! I'm wondering about getting BG out again - as changing the motor didn't cure the problem - and hoping I get a different engineer who might have a different opinion about trying to change the valve!

    Re the showers - they are definitely not electric water heated - and don't think they have an electric pump, unless it's one of the pumps in the cupboard with the thermal store?? These are the two pumps - but assume they are both related to central heating?

    IMG_0080.jpeg IMG_0084.jpeg

    I certainly intend to speak with my neighbours. I know the company they used (see the vans locally a lot) and they have very good reviews on Checkatrade. So will get them around for advice and to quote plus 1/2 other local firms.

    One question re going the combi boiler route - is it likely to result in the need for lots of new piping to be run around the house?

    Thanks again...
     
  6. oldbuffer

    oldbuffer

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    1. Another photo of the motorised valve (which is a Danfoss HS3, not Honeywell) taken from further back would be useful to see if there is any wriggle room with the pipes.
    2. Looks as if its been leaking for ages with all that white crud around.
    3. Shouldn't need any more piping around the house.
    4. You would need a condensate run (inside, white plastic) and a pressure relief pipe (through wall, copper) for a combi. Both in kitchen and with any luck not on show.
     
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  8. heavysoul

    heavysoul

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    Thanks again...

    I've taken a few more photos of the motorised valve... hope they help...

    IMG_0088.jpeg IMG_0089.jpeg IMG_0090.jpeg

    Re point 4 - that makes perfect sense in terms of what I can see coming through our neighbours house wall from their kitchen after having had the work done.
     
  9. oldbuffer

    oldbuffer

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    Looks like a nightmare to access. I'd guess they key questions are:

    1. Is there any room to be gained at the left hand side of your first picture to move pipes left and remove the horizontal connections. Even if this meant disconnecting one or more pipes around the hot water heat exchanger.
    2. The vertical connection could be probably be resolved by removing the head.
    3. I'd be very loathe to change to a Honeywell valve (generally considered the best) because they have a different thread on the nuts, which would mean changing the olives and removing the Drayton nuts. Just replace with same again for simplicity.
    4. If a drain down were necessary, it would cost a lot both in time and replacement inhibitor. You'd probably need two electric pipe freezers, I woudn't trust a gas based kit not knowing how long it would need to be frozen.
    5. Two possibilities:
    5a. Find a specialist Gledhill Boilermate repair company. There used to be one based in Reading who had a very good reputation, but I can't find details. There seem to be a few on the internet. They are most likely to know which pipes can be disturbed with least risk.
    5b. If you are in or around London, try Pimlico Plumbing. Very expensive but very good.

    Good luck
     
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  10. heavysoul

    heavysoul

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    Lots to think about... I really appreciate the time you've taken to answer my questions... enormously helpful.

    Cheers...
     
  11. McCombi

    McCombi

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    Do you have different heating zones in the property?

    I’ve never seen zone valves fitted alongside thermal store I don’t think.

    Sorry not much help to your questions but think they have been covered pretty well, I’m just trying to work out in my head how a zone valve works alongside a thermal store and how a faulty switch on one would affect heating coming in with no demand as I would have thought the zone valve would be after the store and not before it if that makes sense to anyone reading?


    Edit.

    Ignore my drivel, never seen a boilermate 3 model by looks of it, didn’t realise they come with diverter valve as standard
     
  12. heavysoul

    heavysoul

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    My knowledge is pretty bad on these things I’m afraid - so I’m not 100% sure what heating zones are.

    We have one thermostat which is on a landing on the first floor - so middle of the house. Most radiators have thermostatic controls - although a few radiators on the ground floor don’t (kitchen, dining room and hallway near front door - I’ve never understood why these don’t have the thermostatic control). We’ve always struggled to get the temperature as we want it in the right rooms.

    Not sure if that answers your question... I’ve probably gone off at a tangent ;)
     
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