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Ask The Trades › DIY Forum › Plumbing Questions › Water too hot

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Water too hot (Read 15944 times)

Pineapple GDPR opt-out	Water too hot Sep 22^nd, 2011, 9:48am Hi Our hot water is hotter than normal - too hot to keep your hands in but not scalding. I turned down the cylinder stat from 60c but it hasn't made any difference. Turning it right down makes the boiler go off and right up makes it go on, so I'm wondering what else could be at fault? Thank you.
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #1 - Sep 22^nd, 2011, 11:36am Hi. Could be a couple of things but we need to know more about the system. Could be a faulty cylinder stat, or a motorized valve. Is the problem worse when the heating is on.
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Pineapple

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Re: Water too hot
Reply #2 - Sep 22^nd, 2011, 11:57am

Haven't tried it with the heating on due to the time of year. The system is gravity fed. The heating can come on independently of the hot water. The bathroom radiator comes on with the hot water. The boiler is a Potterton Prima F.

We used to have to replace the motorised valves every other year as they were so unreliable, but we haven't had any bother recently.

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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #3 - Sep 22^nd, 2011, 2:09pm I would imagine it's fully pumped, do you have 1 x 3 port valve or 2 x 2 port valves.
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Pineapple GDPR opt-out Total Thanks: 147 For This Post: 0	Re: Water too hot Reply #4 - Sep 22^nd, 2011, 9:54pm thescruff wrote on Sep 22^nd, 2011, 2:09pm: I would imagine it's fully pumped, do you have 1 x 3 port valve or 2 x 2 port valves. I wouldn't know the difference.
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CWatters Super Member Offline "Daddy fick it" says James Posts: 5150 Total Thanks: 58 For This Post: 0 Gender:	Re: Water too hot Reply #5 - Sep 22^nd, 2011, 10:08pm Valves are electrically operated (so they have a wire) and look something like this. How many do you have and which type... Two port: Three port:
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Pineapple GDPR opt-out Total Thanks: 58 For This Post: 0	Re: Water too hot Reply #6 - Sep 23^rd, 2011, 7:20am Thanks for the pictures. My system is a two port. (BTW, if it comes to it, is it possible to change the box on top without having to drain down the system?)
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #7 - Sep 23^rd, 2011, 10:32am Do you have one or two of them. Need info, make and models etc.
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Pineapple GDPR opt-out Total Thanks: 147 For This Post: 0	Re: Water too hot Reply #8 - Sep 23^rd, 2011, 11:31am The two valves are made by Honeywell. The writing on the top is F3-9419. http://www.mediafire.com/?b3zdnvsgcvydqdd http://www.mediafire.com/?wl21kac8b6w7hd1
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #9 - Sep 23^rd, 2011, 1:30pm Don't appreciate getting spammed by mediafire or anyone else. Use the forum facility next time please.
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Pineapple GDPR opt-out Total Thanks: 147 For This Post: 0	Re: Water too hot Reply #10 - Sep 23^rd, 2011, 10:43pm thescruff wrote on Sep 23^rd, 2011, 1:30pm: Don't appreciate getting spammed by mediafire or anyone else. Use the forum facility next time please. Apologies...I couldn't see how to attach pics. I dislike spam as much as the next guy.
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #11 - Sep 23^rd, 2011, 11:32pm I would change the cylinder stat, or make sure it's making a good contact to the cylinder
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Pineapple GDPR opt-out Total Thanks: 147 For This Post: 0	Re: Water too hot Reply #12 - Sep 23^rd, 2011, 11:45pm Cheers, I'll change the stat.
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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #13 - Sep 24^th, 2011, 9:10am Check whether the cylinder stat is closing the MV and shutting the boiler off, in the HWS onltmode
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Re: Water too hot
Reply #14 - Sep 24^th, 2011, 9:51am

Quote:

Turning it right down makes the boiler go off and right up makes it go on...

If it really is controlling the boiler (and the central heating is off) it's hard to see what could account for the water getting too hot. However, normally you only have to turn the dial a few degrees for it to click and the boiler fire up or shut down. If it only controls the boiler when you turn it all the way up/down then I agree worth trying another stat.

One problem with hot water systems is that 60C is hot enough to burn a child but if you turn it down there is a risk of Legionaires disease. I did wonder if somone had just turned the stat up. eg perhaps it set to say 50C before and someone turned it up or knocked it? Sorry if thats a rather obvious suggestion.

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thescruff Global Moderator Trade Member Author Offline Who said plumbing was easy. Posts: 6037 Total Thanks: 147 For This Post: 0 Gender: Trade: Plumber	Re: Water too hot Reply #15 - Sep 24^th, 2011, 11:15am The stat should be 50-55c depending where it positioned
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Re: Water too hot
Reply #16 - Sep 24^th, 2011, 11:17am

thescruff wrote on Sep 24^th, 2011, 9:10am:

Check whether the cylinder stat is closing the MV and shutting the boiler off, in the HWS onltmode

I moved the stat down to 55c from 60c, which I understand is the recommended setting.

Sorry to be dim, but are you saying that the spring-loaded lever should move, or do I have to listen out for a click?

Also, what is HWS on/tmode?

« Last Edit: Sep 24^th, 2011, 11:18am by Pineapple »

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