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    DIY Help: Low hot water pressure from water heater

    Friends,
    Recently to change my tap, i switched off my heater and touched the under part of pressure release valve (some bit water went out through drain). Afterwards, when the tap was fixed and all were normal.
    But I noticed that the hot water pressure went down. The manufacture is "Santon".
    I cant find much settings in the heater and document and everything seems to be in order.

    Once I release the pressure, does it take some days to build up?
    Is there any tweak to be done to the "Line Strainer" or "the adjuster below" to bring more pressure for hotwater?

    19 Comments

    Original Poster

    I've attached an image of the controller below.. ( I hope its name is pressure release valve)
    http://a.imageshack.us/img28/1636/photo1gp.jpg

    you need to up the pressure again. normally there is a pressure gauge it should be in the green zone about 1 bar ish. not sure where the valve would be though they are all different

    just needs to be filled again there should be a tap somewhere near the boiler

    best not to mess with it, i'd get someone in to sort it.

    by heater do you mean boiler?

    What do you mean by the pressure being low?

    Original Poster

    thanks guys.
    @Plum -> Yup, i meant Boiler.

    There is a tap (not exactly a tap) but a control , but its a again a pressure release .. Tried turning it with force, but still the pressure is same.. (the value name is Reliance water controls though its not turning)

    Can you please give me the technical terms of the valve etc.. or a good diagram to understand and search in google
    Edited by: "getknk" 23rd Jul 2010

    getknk

    thanks guys.@Plum - Yup, i meant Boiler.There is a tap (not exactly a … thanks guys.@Plum -> Yup, i meant Boiler.There is a tap (not exactly a tap) but a control , but its a again a pressure release .. Tried turning it with force, but still the pressure is same.. (the value name is Reliance water controls though its not turning)Can you please give me the technical terms of the valve etc.. or a good diagram to understand and search in googleEdited By: getknk on Jul 23, 2010 08:28: .



    What you are looking for is a mains feed to your boiler. This what will bring the pressure up.

    My own boiler has a flexible hose that I connect. I then open up the valves and let the pressure come up to the correct level before stopping.


    It sounds like you opened the release valve, which has let out some water from your closed system which you need to replace as above.

    For some installations the mains is perminently attached and you simply need to open and close the appropriate valve.
    Edited by: "Plum" 23rd Jul 2010

    as above, only fill it to somewhere between 1 & 2 bars and no more

    Original Poster

    hi Plum.. thanks for coming to help me again..
    Spent around 2 hours on the control .. I dont have an extensive system as the image.. but just a small water control like below.. http://www.goodreason.co.uk/images/product/pressure_relief_121213369226_585.jpg
    Still the hotwater pressure is low

    Have you put in a new tap or just installed the old one? Reason I ask is that I bought new taps for my bathroom and the pressure that comes out the hot side is pathetic due to there being a restriction in the tap that slows the water down.

    The cold tap is fine and if I take the tap off and let it flow straight out it is also perfectly fine, just the damn tap that causes the problem.

    getknk

    hi Plum.. thanks for coming to help me again..Spent around 2 hours on the … hi Plum.. thanks for coming to help me again..Spent around 2 hours on the control .. I dont have an extensive system as the image.. but just a small water control like below.. Still the hot water pressure is low



    If you have a boiler I am pretty sure you must have more valves that this one in the pic (insert confused/thinking smilier). A boiler must have at least a cold feed and hot outlet for water as well as inlet and flow for radiators. This as well as the gas supply. These should all have valves on as they enter the boiler? Sorry, not sure if we are talking as they say at cross purposes?



    However it sounds like you are saying it is the flow rate coming out of the hot tap you have a problem with. If that is the case then it has nothing much to do with the actual boiler pressure and is more likely to be the new tap as Satan_Claws says. I assume you have your taps isolated with a flexible hose with stop valves on and have opened both fully once you fit the new tap.

    Is the hot slow even when it is the only tap running?

    I guess there is a slight possibility the tap is blocked or faulty, but I have never had this. You may also have got something in the pipe while it was detached.

    If I had this problem I would take off the hot flex and try running it in to a bucket or something to check the flow. If when you put it on the tap it is much less then the tap is at fault and you can either live with it, take it back as faulty/not fit for purpose.

    The way to check the flow rate is not by how fast it spurts out but by timing how fast it fills up a container. Some bigger bore taps don't look like they are as fast because they are not putting the water under pressure to come out.

    You welcome to pm me if you want to go through anything in detail or think I can help anymore.

    Original Poster

    i've given vote for u.. liked the comment (i'm not sure how to give rep previously) for ur extra effort.. thanks again
    I'm trying to figure out any pipe, but cant find any yet.. I'm in a flat.
    When i start the hot tap, the pressure is high.. but it reduces, so i believe its normal 1 bar only..

    getknk

    i've given vote for u.. liked the comment (i'm not sure how to give rep … i've given vote for u.. liked the comment (i'm not sure how to give rep previously) for ur extra effort.. thanks againI'm trying to figure out any pipe, but cant find any yet.. I'm in a flat. When i start the hot tap, the pressure is high.. but it reduces, so i believe its normal 1 bar only..



    If you are talking about the pressure gauge on the boiler, it should only increase as you heat the water.

    If you are saying the water flows hard out and then slows then this may be because the boiler is having trouble heating the water and therefore slowing the flow to get the correct temp.

    I would still take pipe off the tap and see if it does the same thing. This way you can see if the tap is the problem.

    Being in flat should make any difference to the setup.

    Original Poster

    Hi Plum.. I was going through some technical terms..
    Let me explain now a bit more..
    Before that.. hope I wanted to verify if the terminologies are correct
    1. Pressure release valve aka combination valve (photo I've taken and put in the 1st post)

    2. Tundish http://www.dundeewharf.com/boiler/tundish.jpg

    3. Schematic diagram http://a.imageshack.us/img257/6520/schematicdiagram.jpg

    Original Poster

    - The only thing i did (probably a mistake) is I turned the "T&P Relief valve" and "Cold water combination valve" , hence the pressure went down
    document: docs.google.com/viewer?url=santon.co.uk/doc…pdf
    - These are two settings I can find in the boiler.
    - I've seen water going down the tundish -> discharge pipe once i move the valves above.


    So the query is , how we can put the pressure back to the hot water? Is this a feedback system?

    Edited by: "getknk" 24th Jul 2010

    Ok..

    Sorry I now realise why I thought we were talking at cross purposes, I have not come across these water heaters before.

    I have had a look at there seems to be a procedure for commissioning on page 11.


    There is also a procedure the re-pressure the expansion vessel if the pressure drops below 3.5bar, with a car tyre foot pump. on page 12 section 7.5




    There is also a procedure for re-commissioning on the same page next section 7.6

    The other possibly relevant part I have seen is under fault finding on page 14 under no hot water flow.

    Actually as I am writing this I can see the whole of section 7 regards maintenance and may be worth working through, particularly 7.3 cleaning the strainer.

    I will read through these a couple of times to see if I can suggest a order of things to try, but at the moment I would suggest recommissioning procedure first if you have not done this already.

    edit I have had an initial read through and I would def go through the recommissioning procedure, then the commisioning procedure and then if those don't solve I would check the strainer. I am guessing if you have not done these things you may have air in the system (I maybe talking out of my hat).


    I found this general guide to your type of water heating system.


    Edited by: "Plum" 24th Jul 2010

    It's a pressurised hot water cylinder BTW

    Original Poster

    thanks a lot guys.. I feel its more related to "Expansion Vessel" charge pressure.. Will have a word with my owner and find his thoughts as well
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