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New combi install, help needed

Discussion in 'Plumbing and Central Heating' started by LeeroyK, 28 Aug 2021.

  1. LeeroyK

    LeeroyK

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    Hi All,

    So I decided to switch from a system to combi boiler, a 35kw unit rated for 16ltr/m. Stopcock has a non return and pressure limiting valve, currently 3.0 bar static.

    It's just me in the property so I was looking forward to the mains pressure shower.

    I'm getting just over 6ltr/m from the upstairs bathroom hot tap with no other draw on the system.

    Really not sure what to expect from a combi but this doesn't seem normal.

    There are other problems with the install, either trapped air or a dead leg so combi fires on cold water briefly (obviously it doesn't heat the cold water). But this indicates a pressure issue.

    Have spoken to installer, his response is to fit a non return valve on the cold feed to the boiler but I'd rather get the underlying issue resolved.

    I look forward to hearing your thoughts, help needed!
     
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  3. Madrab

    Madrab

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    Did the installer not do a check on the HW delivery at all outlets? It's part of the commissioning process and benchmark.

    If the cold is bouncing back to the boiler when the cold is run then again that's his issue, if it is an issue to you he should be sorting it. He's right that an NRV should sort it but that's not the point. Is the boiler feed tee'd close to the cold water outlet?

    I really don't understand installers like that, where's the work ethic and customer service. If he installed the system and there are teething/snagging issues then he should be there to sort them out, not just fling ideas at you. Granted if other bits are needed to correct any issues then there would be a cost attached to that but never the less.
     
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  4. LeeroyK

    LeeroyK

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    Man, you should see the pipework. I questioned him on it and he gave some fair answers but still... looks shocking.

    There was another reason for getting the boiler done, there was a small leak from an en suite shower, behind the cylinder, behind the wall.

    That would have cost a lot of money to sort out so I thought get the cylinder out and gone, access to the plaster board, cut a hole, reflux the pipes and we're all good.

    On the day the installer wouldn't do that because 'it's not in the contract' and just capped off the h/c feed to the shower. The cold is a 22mm feed with a isolation tap on it, then capped. Could probably be bled.
     
  5. Madrab

    Madrab

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    Usually when a combi hunts it is because a cold tap on the same pipe as the boiler feed is run and it then pulls on that cold feed, the boiler registers the water movement and fires up the fan, then the pressure settles and the boiler shuts down as there is no actual call, a NRV stops the pull.

    Unless the job behind the cylinder was discussed and agreed then it wouldn't be reasonable to expect the work to be done non gratis. That being said a quick discussion and agreement that there will be an additional cost for the work to be done then that wouldn't be unreasonable either. The only other factor would have been time and whether there was enough left to do the additional work.

    Your installer sounds like a bit of a plonker but of course we are only getting one side of the story ..... :unsure:
     
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  6. LeeroyK

    LeeroyK

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    We're all plonkers in our own way I guess ;)
    I'm probably the nightmare client who kept checking on him every 2 hours and wanted him to do work outside of remit.

    I just didn't think it'd be an issue, to my mind, while he was there, cut a hole in the plasterboard and reflux, 10 mins max. I'd do that for my customers if I were a plumber. The pipework may have even been exposed, I couldn't know till the cylinder was out. It never crossed my mind that there would be any resistance to the idea.

    I thought the NRV was the quick and dirty fix but it sounds like you think that's an acceptable solution to the problem rather than checking pressures and bleeding that dead leg?
     
  7. LeeroyK

    LeeroyK

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    Btw, I get about 17ltr/m on the pipe feeding the boiler and 6ltr/m at the hot taps upstairs with no other draws on the system.
     
  8. oldbutnotdead

    oldbutnotdead

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    Expecting him to fix a leaking shower as part of a boiler install was cheeky & not really on- that is a 'can you just' job, if the request had been accompanied with some folding then the response might have been different (especially if yr fitter was on a wage rather than 1 man band).
    The disappointing flow rate & the hunting are both install problems & shouldn't be chargeable. Pics of the pipework might be helpful, have you checked that all the iso valves are fully open (especially if you have the cheap screwdriver slot typed), have you had a look at the user manual for the boiler to see if there are any programmed limiters on the hot water?
     
  9. Madrab

    Madrab

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    An NRV is a well know fix to the boiler hunting issue. It is a particular headache where the mains feed to the boiler and outlets is all 15mm. Unless you want to go through a cold mains supply and distribution pipework survey and alteration to it then the NRV is the best solution. That being said it is something the installer should look at TBH

    Could the hot tap upstairs be a modern mixer/tap with a water saving aerator? What are the other HW outlets like? What is marked in the benchmark?
     
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  11. LeeroyK

    LeeroyK

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    They're just standard 20+ year old brass taps upstairs, same on the basins.

    All the valves are open from what I can tell but I did notice he's used a little plastic elbow that could be restricting things?
     

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  12. ianmcd

    ianmcd

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    What does reflux mean ?
     
  13. LeeroyK

    LeeroyK

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    I just mean resolder the elbows. If it still leaks then the shower mixer would need replacing from the other side.
     
    Last edited: 28 Aug 2021
  14. oldbutnotdead

    oldbutnotdead

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    Irritates me when fitters work on a copper system & bang in a load of plastic cos it's quicker/easier for them. The internal bore of placcie 15mm is only about 11mm to start with, the inserts drop that even more so it won't be helping.
    What sort of flow & temp are you getting from the kitchen hot tap? And I really meant pics of the boiler pipework and valves, sorry for confusion.
     
  15. LeeroyK

    LeeroyK

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    some more pics...
     

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  16. oldbutnotdead

    oldbutnotdead

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    That's all a bit shoddy...wonder why he didn't run the F & R behind the boiler? Would have had to get creative with the Magnaclean I suppose- under the worktop mebbe? Looks like the iso valves around that cleaner are closed...did you do that or did matey leave them like that (if they are closed then heating won't be working)
     
  17. LeeroyK

    LeeroyK

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    Thanks for picking up on on that. Those pics were taken mid install before it was all hidden behind a cupboard, figured they'd be clearer/easier to see what's going on. Valves are now open on the magniclean.
     
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