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Discuss Boiler firing when CH and HW are off! in the Oil and Solid Fuel Forum area at UKPlumbersForums.co.uk.

  1. Austin Hayward

    Austin Hayward New Member

    Hi all,

    Looking for some advice as my boiler is driving me up the wall!

    Moved into the property in July last year, house is approx 16 years old. Since the day we moved in I can’t work out how the CH or HW work, but it’s worked so i’ve just left it. I have no HW tank in the house (combi boiler) or a thermostat, all radiators (except utility) have TRV’s fitted.

    Boiler is a ‘Boulter Camray 5’ with a ‘Boss Therm’ programmer unit and is located in the garage. It seems I have no control over the boiler from the programmer unit. I have tried setting times for both the CH and HW to come on (morning and evening) but the boiler just seems to carry on regardless. I can set both the CH and HW to off on the programmer and the boiler still fires regularly and my radiators heat up. I can physically stand in front of the boiler, hear it fire up and look at the programmer and both red lights be off (no demand), CH and HW both set to OFF.

    Recently we went on holiday for a week and I didn’t want the CH blasting away for the week. Seen as I have no control from the programmer, I switched the boiler off at the fuse spur. This caused a world of pain, got back from holiday and boiler just wouldn’t fire and kept going to lock out. Engineer came out and diagnosed the burner to be faulty, low oil pressure also. New burner, massive hole in my pocket but we had heat again!.. only to find the expansion vessel had a slight leak, and could have been leaking onto the top of the burner control box, so new expansion vessel aswell.

    Now my oil is rapidly decreasing, 1 bar on the in home display every 2 weeks (1300L tank). And I think it’s because the boiler is just constantly kicking in throughout the day even through the programmer is set for it to be off...

    Either i’m missing something here and have no clue how my system is meant to work or I have a faulty part. I’ve done some reading up and there is a lot of talk about the diverter valve. I found this on my boiler, it’s a ‘Danfoss Type HSA3’ which is a 3 port valve. I found the lever and can freely move it between the 2 positions, is there any other tests I can do to check it’s ok?

    Can someone please give me some advice on what the issue may be before I lose the will to live! Ha Ha

    Thanks in advance!
    Last edited: Jan 13, 2019
  2. SimonG

    SimonG Trusted Plumber

    If it's a hsa3 then that's your problem. The camray 5 needs a special head. Sounds like people who don't know what they are doing have played with the boiler at some point.
  3. SimonG

    SimonG Trusted Plumber

    Also doubt you would have needed a full burner, but without seeing who knows.
    • Agree Agree x 2
  4. Austin Hayward

    Austin Hayward New Member

    Probably not but Engineer that came said it could be a number of things, and without going through each part one by one a week before Xmas with a 3 year old in the house I told him to just get me a new burner, one in there had been in for 16 years. Didn’t want to replace one part then 6 months later something else fails, seemed logical to just swap out the whole unit.

    Apparently the boiler had been serviced every year, but the engineer that came out for the lockout issue said it hadn’t been running right because the flue is all choked up and black. It was an old dear living here before, so no doubt she’s been conned.

    The boiler is working and I have heat and hot water, I just have no control over it at all, or so it seems.

    Are these Danfoss HSE3 valves common to failure? Are there any other symptoms I would notice if it has failed?
  5. MikeJhn

    MikeJhn Active Member

    Check the simple things first i.e. the Frost Stat if that has failed on or been turned up to maximum, then the symptoms you describe could happen.

    You have changed the valve description, please check which you have?
    • Like Like x 1
  6. Austin Hayward

    Austin Hayward New Member

    Something I have just noticed... programmer is set to off, no demand. I turn up the thermostat on the front of the boiler for the HW, boiler kicks in to heat up the water in the tank. But a few of the radiators in the house are now getting warm.

    Would this point to the valve being stuck in the mid position?
  7. SimonG

    SimonG Trusted Plumber

    Sometimes you just don't have to over think things. Post #2.
  8. MikeJhn

    MikeJhn Active Member

    Go back to post 2, do you have the wrong valve fitted, post exactly what you have, you changed model in your post's.
  9. Austin Hayward

    Austin Hayward New Member

    Apologies I misspelt on my other post. I have a ‘Danfoss Type HSA 3’ diverter valve fitted. Attached a photo of the label on the side of it.

  10. SimonG

    SimonG Trusted Plumber

    That's the beast. Don't forget the CD on the end if you order a new one.
  11. Austin Hayward

    Austin Hayward New Member

    Update for you... removed the actuator from the valve, switched between CH & HW, no movement at all, couldn’t even here the motor trying to drive. Valve shaft was also very tight, did move freely after I turned it a few times.

    Thought it would be best to replace both. Ordered parts and fitted today... SUCCESS!! now when only the HW is on the rads aren’t getting warm like before. When both HW and CH are both I don’t here the boiler kicking in randomly anymore. Hopefully it runs more efficiently now and doesn’t go through oil like no tomorrow!

    Thanks SimonG! You were spot on!
    • Like Like x 3
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