Pressure Problems With New Boiler + Ceiling Damage

Discussion in 'Plumbers' Talk' started by Yorkie218, Dec 4, 2017.

  1. Yorkie218

    Yorkie218 New Member

    Hi all,

    We recently had a new combi boiler fitted in place of our old standard boiler beacuse we were told that the new combi boiler would improve our water pressure, which it has. BUT, the water isn't hot enough so we've had to adjust the stop cock to lower the mains water pressure in order for the water to heat up, this is the only way we can get the water hot enough ! .. so now we've got a combi boiler which is worse than our old one ! .. the waters hot but the bath takes ages to fill ! ...can this be adjusted ?

    Also, during installation, some jobs weren't finished off properly and some damage was done to one of our ceilings. We've been back in touch with the installers but they've turned a deaf ear to our problems.

    How do we stand with regards to these problems ?

    Thanks in advance.

  2. Mike83

    Mike83 Active Member

    Make sure the how water thermostat on the boiler is turned up full.
    Also in the winter a combis performance will drop a little due to the incoming main being colder. This will improve through spring and summer but dip again come autumn and winter.
    Also the output of the boiler has a big influence over the quantity of hot water available.
    What boiler do you have.
  3. nigel willson

    nigel willson Well-Known Member

    Have you payed them yet? Turning down stopcock does alter “pressure”. You should call them back if your not happy with it. Send them a letter!
  4. Hi Yorkie.

    A combi will improve water pressure since it's driven directly by the mains. This does not mean that the flow will increase - they are different things.

    If your old system was supplied from a cold storage tank in t'loft and a hot cylinder in t'airing cupboard, chances are the flow was pretty good, but the pressure behind it was pants - ie you could stop the flow with a finger over t'spout.

    A combi can be great - it'll provide constant hot water for your sink and basins and showers - awesome showers. But, you will find their limit when trying to fill a bath - it will almost certainly take longer than an ordinary system.

    The answer is a bigger combi - but it's too late for that now.

    However, your boiler SHOULD provide hot water. If it doesn't, it's likely your cold flow is too high, so a wee restrictor may have been required in the cold inlet to the boiler.

    What make and model is it?
    Astramax likes this.
  5. Yorkie218

    Yorkie218 New Member

    Thanks for the replies. The boiler is an Ideal Logic Combi C and it's already paid for. The temp dial on the boiler is turned to full.

    Last night it stopped working, the display on the boiler said low water pressure so we turned up the stop cock and turned on 2 isolating valves
    which are connected to a pressure gauge and our mixer shower ... the boiler then came back on. It's working ok at the moment, the pressure
    is better but the water isn't as hot as we expected, maybe it's because of the cold winter water as suggested. It's warm enough to wash but
    isn't has hot as our old system.

    Also, how do we stand with regards to the damage done to our ceiling ? ... if they've done the damage they should put it right ?

    Thanks again.
  6. What Kw rating is the boiler?

    Yes, open up the stopcock fully - that's not the way to control the boiler!

    What you may find is that turning the hot tap closed a bit should heat the water further - try that - but, of course it'll now take even longer to fill your bath or basin.

    (Explain what these two valves are that's connected to a pressure gauge).

    As to the damage, that should have been agreed and explained before they took on the job. It's usually called something like 'making good afterwards', and they should have made it clear whether or not it was part of the job. If they didn't, they were remiss. But don't know where you are legally on this.

    Anyhoo, what kW is the boiler.
    Astramax likes this.
  7. Yorkie218

    Yorkie218 New Member

    The boiler is an Ideal Logic C 30 = 24.2kw max 6.1kw min for non condensing, and 25.6kw max 6.4kw min for condensing.

    Explanation of the Valves & pressure gauge ...

    Next to the airing cupboard is a mixer shower which was supplied by cold and hot water pipes which are still there.
    When they removed the hot water cylinder, pump and all the other pipes in the airing cupboard they added an extra
    15mm pipe from the loft where the boiler is fitted. This new pipe is connected to a pressure gauge which is then connected
    to the original cold water inlet pipe. The gauge range is 0 - 4 bar and at the moment the black hand is at 2.5. The gauge has
    also a red hand which is on 1.5, I presume this is some kind of marker ? The gauge is connected to both pipes with isolating valves
    similar to the ones used to connect a washing machine.

    When the installers left the two isolating valves were turned off, they said to only turn them on if the pressure valve
    dropped below 1.0. ... to be honest, because these valves and gauge are connected to the mixer shower pipes I didn't
    know if they were to control just the shower pressure or the whole system ... it was never explained to us.

    Hope this helps.
  8. koolpc

    koolpc Well-Known Member

    Naff fitters. Probably a naff boiler too!
  9. Your boiler is basically a 30kW jobbie, so should give you a perfectly good hot water flow. It's the same output as mine, and that gives plenty of hot water for the kitchen sink, and superb hot and gushing showers. But, it will struggle to fill a bath as quickly as a conventional system - that's just the way they are.

    BUT, the water should be 'hot'.

    When you turn on your hot kitchen tap, how fast does the water come out - is it very powerful almost splashy? And ditto for the cold? If so, then it may simply be that the cold mains supply is too powerful so should have a PRV fitted and set to, say, 3 bar to 3.5 bar (But, really, the mains pressure should be measured first).

    Ok, you turn on your hot kitchen tap and water gushes out - but it's not 'ouch' hot? Right, try turning the tap down so that it's at a decent flow rate, but not 'gushing'. Is it now 'ouch'?

    I have to say that our own hot kitchen supply isn't scalding during these months - the water is 'hot' but you can start doing the dishes without having to add cold first.

    Showers are awesome, tho', and you can keep tweaking it up until it's oooooooh - AAAHHHHHRGH. (That's a technical term).

    But baths will always be slow to fill with a medium sized combi.

    Ok, different issue - these isolating valves and pressure gauge. Oops - close them right away... That's used ONLY to top up your sealed system pressure if it drops to below the red needle level, in your case 1.5bar. If you allow the pressure to hit 3 bar by keeping it open too long, then you'll have forced open your safety vale, and this might then not reseal again properly - keep an eye on the pressure, see if it falls slowly over a few weeks.

    These valves have NOTHING to do with your shower.

    A 30kW combi will take around - ooh - a good 10 minutes to 'fill' a bath. That is one of their drawbacks. If you are a 'bath' person and have them daily, then perhaps a combi wasn't a good choice. However, all it really means is that you need to start drawing a bit sooner than before.
    Astramax likes this.
  10. Yorkie218

    Yorkie218 New Member

    In the kitchen it is fairly powerful so I've turned the stop cock down which has helped. Also we don't fully open
    up the taps as suggested - restricting the flow makes the water hotter.

    As for the pressure gauge and isolating valves, I didn't know these would be needed, it could prove to be
    a real nuisance having to check the pressure all the time ... never had to do this sort of thing before on
    previous boilers.

    Anyway, thanks for the help and advice, it's much appreicated.
  11. JP.

    JP. Screwfix Select

    Why on earth a combi boiler was fitted in the first place is beyond my comprehension
  12. Turning down a stopcock is not the answer.

    For a normal tap, just open it a bit less. For your bath, just open it a bit less. You'll get hotter water.

    But...your bath will still take at least 10 minutes to fill. That's the 'con' of a combi.

    If your mains pressure is truly too excessive, then the solution is to fit a PRV (pressure reducing valve) on the mains inlet and tweak that down to 3 or 3.5 bar.

    But your bath will still take ages to fill.

    You say you swapped to a combi to increase water 'pressure'? Well indeed it has - you water pressure is awesome. But that is not, as you have discovered, the same as 'flow'. A combi flow is typically 12lpm which is perfect for ta\ps and showers - but not ideal for baths.

    Solution - give give it a few more minutes. Pour yourself a drink.

    As for the pressure gauge, that shouldn't be a problem (or at least it wasn't until you opened both valves...). A decent water-tight system should maintain its pressure for many months, possibly years (like mine...). But you should have been taught what to do in the event of a pressure fall below that red line - it's straight forward.

    Now that you've opened these valves and possibly overdone the pressure, you need to (a) get it back down to 1.5bar (if it's much higher than this - simple bleed a rad) and (b) keep an eye on it - weekly - to check that it isn't now falling.
    Astramax likes this.
  13. The Teach

    The Teach Well-Known Member

    The boiler is fitted with a flow regulator,so there is no need to reduce the cold water mains.

    Maybe the boiler has not been set up correctly or there is insufficient burner pressure due to undersized gas pipe,who knows but only onsite testing will prove correct installation.
    The bath will fill slower but not excessively slower.

    The damage caused during installation,get an itemised written estimate and post (royal mail singed for 1st class) to the installer.
    Deleted member 33931 likes this.
  14. Yorkie218

    Yorkie218 New Member

    Thanks again for the info everyone, the pressure has increased and now fluctuates between 2.5 & 3.0 so I'll bleed the radiators has suggested.

    I did think 2.5 was ok but I'll try for 1.5 if that's the correct pressure.
  15. The Teach

    The Teach Well-Known Member

    The boiler pressure gauge indicates the pressure in the radiators and a part of the boiler,it has nothing to do with water tap pressure/flow.

    try to release some pressure down to 1.5 when radiators are cold OR 1.25 when radiators are hot.

    2.5 or 3 bar is far to high and will lead to other problems and possibly a boiler breakdown,hey we dont want that ;) its winter.
  16. CraigMcK

    CraigMcK Well-Known Member

    I expect the installer has fitted a secondary heating pressure gauge to stop you having to go into the loft to check it, the two valves will be a filling loop for the heating. They should not be left on, just turned to top the system up to 1.5 bar.

    Regarding the water into the bath. You will never get anything close to what you had with a combi of that size, if anyone said you would they lied. You had a hot water store sitting around 60C so your bath would be mixing hot and cold to get a suitable temperature, your boiler would struggle to get 60C at any flow rate, and just now you will be getting flow around 12l/min at 35~40C. By the time your bath is full the water is "cold" at that rate. My boiler is much larger and it's okay for baths, but if the house was not already fitted with a Combi I would not have replaced it with one
  17. Yorkie218

    Yorkie218 New Member

    Thanks for the input, it's appreciated. I would never have gone for a combi boiler if I'd have known all this, I could kick myself !

    The old system worked perfect for 11 years then the boiler started to play up so I took the advice of previous plumbers and went
    for the combi option.... also, my neighbour had one fitted and convinced me that it was the way to go ?

    The next step is to replace my mixer shower with an electric one, then we won't be caught out if this new boiler breaks down.
    When our previous boiler was playing up we couldn't get a bath or a shower so an electric one seems to be the best option.

    At the moment I've only managed to get the water pressure down to just under 2.0 even though I bled all the radiators at least
    twice....I'll keep an eye on it and try again tomorrow.
  18. CraigMcK

    CraigMcK Well-Known Member

    You will probably need to drain off some water out of the heating system to get it down. Is there a drain valve near the twin valves? If not you could go the hard route and leave the bleed valve open on a rad (with cup/jug under it) to get some water out of the system
  19. Yorkie218

    Yorkie218 New Member

    No drain valve near the gauge, I'll have to re-bleed the radiators.

    Went in to the loft to look at the boiler, I did notice that the pressure on the boiler pressure gauge was less than
    the one in the airing cupboard, when the downstairs one read 2.5, the boiler one read 2.2.

    Also, if the pressure should be 1.5, is this only on standby ? .. how much fluctuation is there when the boiler
    fires up ? .. how much should it increase when the system is on ?

  20. koolpc

    koolpc Well-Known Member

    1.5 is the norm. This is what mine is at when it is doing nothing

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