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Hot water issue - Glowworm hideaway

Discussion in 'Plumbing and Central Heating' started by OldGreg, 2 Nov 2020.

  1. OldGreg

    OldGreg

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    Hi all.

    Recently moved house and have noticed what I suspect is a fault with my heating / hot water system.

    With the central heating off and the hot water on, the upstairs radiators are getting red hot.

    The boiler is a Glowworm Hideaway 50, and I believe that it’s a gravity fed HW, pumped CH system. I haven’t found any zone valves or additional pumps anywhere, other than the one on the CH pipe next to the boiler.

    I’ll attach a picture, but you can feel the pipes when the HW is on and the HW pipes are hot, but one of the CH pipes is also hot out of the boiler which leads upstairs, the downstairs radiators also Tee into this pipe which is stone cold.
    So it definitely seems as though the boiler is somehow allowing heated water to pass into the CH system when the HW is on and gravity heating the upstairs.

    I’ve had a plumber out, who has pretty much said it’s a quirk of the house and normal. Doesn’t sound right to me that the upstairs cooks when you want hot water (especially in summer)

    Any suggestions of things to check or possibly what the issue could be?

    Cheers

    26F5E331-E682-41FE-B48F-DF1856699367.jpeg
     
    Last edited: 2 Nov 2020
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  3. Chris_W

    Chris_W

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    I’d say there’s a 3 port valve somewhere possibly letting by, or reversed circulation, but I think that only happens to a couple of rads?
     
  4. OldGreg

    OldGreg

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    Thanks for the reply Chris.

    I’ve had a look around for any valves and can’t find any, unless it’s possible they’re installed under floorboards?

    The only valve I’ve found is a manual valve to one side of the water cylinder, but I think this may be the supply from the header tank to the boiler. I’ll add a picture.

    In regards to reverse circulation, the house has been extended downstairs, but it’s all of the upstairs radiators that are effected (4 in total)

    12520029-3CA0-4059-A555-E1930221B25B.jpeg
     
    Last edited: 2 Nov 2020
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  5. 45yearsagasman

    45yearsagasman

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    That's an old gravity hot water and pumped heating set up. Top floor rads getting hot is caused by thermo syphoning. Normally an anti gravity valve was fitted to prevent that. Simple to fit, but will require a drain down. If you want to have more control over your system, then have it upgraded to fully pumped, which would allow you to control hw and htg separately. In Summer you could simply turn off the affected rads by their valves.
     
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  6. OldGreg

    OldGreg

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    Cheers for that, very much appreciated. Looking into anti gravity valves, seems like this is the part I’m missing!

    Any idea what’s involved or what parts are necessary to change to fully pumped, and if there are any other advantages other than having the HW and CH having separate controls.


    Thanks.
     
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  8. 45yearsagasman

    45yearsagasman

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    A conversion to fully pumped requires, motorised valves, pipework, possibly a new cylinder and electrical controls to be upgraded. I've been retired 10yrs, so am out of touch with current pricing. Used to be around £800 when I was at work. Possibly two days labour. Sorry I can't be more precise. To have separate controls will save money on gas usage, but will make the system more controllable. When you come to replacing the old boiler, your system will be ready. Sorry for the delay in responding.
     
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  9. RayCaister

    RayCaister

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    In 1978 I bought a new build with a Ideal vented heat only gravity HW pumped CH system. It had exactly the symptoms you described. I always regarded the hot upstairs rads in the bathroom and small bedroom (airing room) as a "feature" rather than a fault and was quite happy to live with it for 35 years. Now have a bungalow with a combi so no more "features".
     
  10. picasso

    picasso

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    Single check valve where the x is will stop the thermosyphon.

    valve.jpg
     
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  11. stem

    stem

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    I had the same set up in my house when I bought it, complete with a 'Primatic' hot water cylinder. The following summer I converted it to fully pumped with a new indirect cylinder. I was so glad I had when the boiler started leaking in the middle of winter a few years later and had to be replaced. New gas boilers don't work with gravity systems and have to be fully pumped, so because I was already set up that way it was a simple boiler swap and I didn't suddenly have to have everything re-plumbed as an emergency.... Just thought it might be something you might want to consider.

    Also, these old systems without any thermostatic control of the heating or hot water can waste a lot of energy and be quite expensive to run.
     
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