ISAR HE24 Boiler issues.

Discussion in 'Plumbing and Central Heating' started by lowlevelpilot, 10 Jul 2007.

  1. lowlevelpilot

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    Hi guys,

    I have an ISAR HE24 Boiler in my flat that was installed 18 months ago. Since installation I have had numerous problems with the hot water (DHW) running luke warm at best, often cold. To cut a long story short the plumber has been out twice trying to fix this. Now... I'm not entirely convinced this guy knows what he's doing and can't be certain what he did to fix it as I wasn't there but the problem has returned on both occasions after a few weeks and I can't get another guy in as he is the chap sent out by the builders for the warranty, despite asking for someone else. So... I decided to try and learn the boiler and system for myself to help him.

    When a hot water tap is turned on, hot water comes out for 5 seconds then it runs and remains cold/luke warm. The boiler displays (d) and the burner light illuminates as normal. After around 1 min and a few knocking noises including fluctuations in the Pressure guage on the C.H flow pipe ocour and a fault code of L9 appears (heat exchanger overheat). My best guess is the noises I hear are the diverter valve getting stuck resulting in no water passing through the heat exchanger and the subsequent overheat. Does that sound plausible? The central heating works fine although I am confused as to why the pressure guage fluctuates if it's the DHW that has a problem. What should that guage read when not in use and when in use?

    Any help appreciated Thanks.....
     
  2. gas4you

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    When cold gauge should read just over 1 bar, depending on your heating system size this will rise to around 1.8 - 2.2 bar when rads are hot.

    As this sounds like it is a new build property, the idiot who the builder is sending round should have put a call into Ideal under warranty.

    The banging and knocking noises are due to lack of flow through the main heat exchanger so could be DV stuck or maybe pump not working fully or plate heat exchanger blocked, the latter shouldn't be as it is this new.
     
  3. scatmanjohn

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    Strangly enough i had one of these doing just that.

    Found the remains of a plastic carrier bag in the pump :confused:

    I'd look at the pump first off.
     
  4. Agile

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    The pressure gauge is oddly on the flow pipe and the pressure increases about 0.4 bar when the pump comes on.

    I would check the pump connections and see if the impeller is clean first.

    The most likely cause is a blockage somewhere in the boiler and th plate HE is the first place to look.

    That would be confirmed by a thermal survey of the boiler.

    Tony
     
  5. scatmanjohn

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    i like it...so will be using it from now on. :LOL:
     
  6. ACOperson

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    If you have a couple of towel rails fitted then this could also have something to do with it.

    A few weeks ago I came across a plate h/e on an Ideal in a new build, completely clogged with very metallic sludge. Property was about 2 years old. Even though all the rads were new 2 years ago I'm guessing that whichever contractors the builder had in used about half a large pot of acidic Everflux or something when installing and not done hot cold flush / neutralisation, this acid had then eaten away at the insides of the radiators in the place. Also were 3 towel rails in the place, normally full of rust when new anyway....
     
  7. lowlevelpilot

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    Thanks for all your replies. I'm having a look at it tomorrow night and will no doubt be after some more advice when I still can't work out whats going on!!!! BTW no towel rails just 5 normal rads, 2 sinks and 1 shower. Anyone know a good online manual for this type of boiler? Why would the guage on the CH flow pipe fluctuate if it's the Hot water that's at fault? Are they not plumbed seperately?

    :confused:
     
  8. gas4you

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    The same system water goes through the rads as the system side of the plate heat exchanger.
     
  9. lowlevelpilot

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    please pleae please....... does anyone know where I can get a comprehensive manual/data for this boiler? Preferably online, the service guide is useless for telling me how it actually performs its supposed tasks! Why would the DHW have anything to do with the heating loop? How can they possibly be linked? The heat exchangers are seperate and I don't want rad water coming out my hot taps..... :confused: Gas 4 you, thanks for the reply but sorry mate but I don't understand system side? Does the DHW heat exchanger sit inside the heating heat exchanger and share the same burner?
     
  10. Dan_Robinson

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    The manual you have is all you need. If you are having trouble understanding the advice given, or the manual then I would suggest (humbly) you get someone in to take over.
     
  11. gas4you

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    The DHW is provided via a plate heat exchanger. The water heated in the main heat exchanger is sent to one side of the plate heat exchanger via the diverter valve. The diverter valve either sends it 'that way' or if there is no demand for HW and there is for heating it sends the heated water to the radiators. The heated hot water from the main heat exchanger does not physically connect/mix with the dhw out of the taps. The other side of the plate heat exchanger contains the cold mains water that is heated by the heating water heat transferring across to the tap water side via the plate heat exchanger.

    Your hot tap water does not come from the main heat exchanger.

    This is why the guage will fluctuate when dhw is on, it is the same water that goes around the radiators.
     
  12. Dan_Robinson

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    You say the pressue guage is fluctuating - you have a blockage somewhere.

    As has already been said - chances are it's in the plate heat exchanger or its manifiold. Do you have a Honeywell Diverter valve or the older CP one? If the latter then I advise you know, if it needs changing then you have to change the whole left hand manifold.
     
  13. lowlevelpilot

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    gas 4 u......

    superb thanks, got it. Just had the covers off and all became clear. I have now removed and cleaned the pump and diverter valve and this seems to have cured it although it did'nt seem to dirty. DHW is piping hot at all flow rates and CH works great. There's a small plastic tab on the side of the diverter that moves the valve back and forth, could moving this have helped? Other than that cleaning is all I did?? Very strange it should now work after doing not much. It is a honeywell diverter Dan and I appreciate your comments but I'm not the type to give up so I now understand how it all works....Some of which is thanks to you guys so no need for the cowboy from the builders to visit and turn the main tap down to a dribble.

    Ideal offered to send one of their engineers round next week, should I still get him over and explain what I did so he can give it a look over or would he be ****ed off at a call out given it's now working.....All boiler indications are correct and after reseting no fault codes......

    Cheers again for any help
     
  14. Dan_Robinson

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    Glad to hear its working.

    I wouldn't worry about p1ssing them off...

    I was being cautiopnary because unless you know what you are doing it is very easy knacker a part or seal; which could end up very expensive very quickly.


    These modern boilers run very close to the limits, and it doesn't take much to upset them. Every boiler we fit now comes with a Magnaclean, unless there are severe space restrictions.

    It helps eliminate the problems you experienced.
     
  15. Agile

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    I would not advise you to let the Ideal man come under the warranty.

    If the boiler is working on their arrival it could become a chargeable call.

    My advice is to cancel it !

    The lever on the side is only an indicator and cannot be used to operate the valve. They used to have a reputation for sticking but I thought they had been improved now.

    Tony
     

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