Hot Water Cylinder Mixing Valve

[TheArtfulDodger]

Hello:

I am sure that my question will seem quite trivial to the members of this forum, but not for me. For, you see, I am an Electronic and Computer Engineer by trade and I was always taught to keep my hands out of water!

Here's my problem (this description of my system is the best I can conclude after searching the web for quite some time!): I have a gas boiler and an indirect, vented hot water cylinder. As most would know, where the hot water for the taps leaves the cylinder, there is a mixing valve to allow control of the temperature of the hot water while still having hot enough water to heat the radiators!

Here's my problem: A couple of years ago I was having trouble with my hot water and a plumber thought it was this mixing valve so he changed it. As it turned out, that wasn't the problem (limescale build-up) but my mixing valve was gone and I had no control over the hot water temperature except by changing the temperature of the cylinder - not good! Problem just came back and the plumber (diferent plumber) again thought it was the mixing valve so when he said he would change it I mentioned the temperature problem. He indicated that all of the valves now do not permit changing the temperature of the hot water (Health & Safety) with the valve!

So the question: Is it correct that all mixing valves do not permit changing the outgoing water temperature? If not, what information do I need to obtain from the current valve in order to replace the present one with one that can be adjusted?

Thanks in advance for your help.

Sparky

 

[stevetheplumber]

Hello:

I am sure that my question will seem quite trivial to the members of this forum, but not for me. For, you see, I am an Electronic and Computer Engineer by trade and I was always taught to keep my hands out of water!

Here's my problem (this description of my system is the best I can conclude after searching the web for quite some time!): I have a gas boiler and an indirect, vented hot water cylinder. As most would know, where the hot water for the taps leaves the cylinder, there is a mixing valve to allow control of the temperature of the hot water while still having hot enough water to heat the radiators!

Here's my problem: A couple of years ago I was having trouble with my hot water and a plumber thought it was this mixing valve so he changed it. As it turned out, that wasn't the problem (limescale build-up) but my mixing valve was gone and I had no control over the hot water temperature except by changing the temperature of the cylinder - not good! Problem just came back and the plumber (diferent plumber) again thought it was the mixing valve so when he said he would change it I mentioned the temperature problem. He indicated that all of the valves now do not permit changing the temperature of the hot water (Health & Safety) with the valve!

So the question: Is it correct that all mixing valves do not permit changing the outgoing water temperature? If not, what information do I need to obtain from the current valve in order to replace the present one with one that can be adjusted?

Thanks in advance for your help.

Sparky

what you have by the description youve given is a heat store system and yes the mixer valve should be adjustable any thermostatic mixing valve with the right dimensions should be ok reason you have it is the stored water will be hoter than necessary for hot water
easy way to check that this is the system you have is preasure on your basin if you can stop it with your finger over the tap ignore what ive said as it should be at mains preasure on a heatstore system
unvented cylinders dont normally have a tmv
is there a name on the cylinder ?

 

[TheArtfulDodger]

Hello, Steve:

I wasn't sure, from the terms & conditions, whether or not we were allowed to mention brand names. Anyway, it is a Gledhill Boilermate II.

With the first valve I could alter the tap water temperature quite considerably. With the last one I couldn't change it at all, at least not that I could judge from feeling it. I haven't tried this valve because the guy said that it wouldn't change the temperature of the tap water.

Unfortunately, there aren't any names or part numbers on the valve itself.

Thanks again for your help.

Sparky

 

[migoplumber]

as steve says should be adjustable, health and safety dictate certain temperatures required at point of use, generall your store water will be at 65+ to eliminate legionella risks, your pipework carryin this 65+ water will arrive within 1metre of p.o.u.
from there you can use a further blending valve to reduce temperature further to posibly 42 degrees (this one varies depending on site and conditions, but generally falls between 38 and 48 degrees - could be different in domestic situations, i dont know)
the idea behind blending valve on top of cylinder is to give you more hot water, storing hot water at say 80 degrees ( if you have solar or solid fuel ) then mixed with cold water would up your storage levels from 200 to 250 litres

 

[TheArtfulDodger]

Hi, Everybody:

Well, I have solved the "problem"! Either the guy didn't know what he was talking about or he was trying to be clever! At any rate, it turns out the valve does allow variations, from full HOT to full cold!

So, I guess the need to change anything can wait for awhile!

Many thanks to all who replied and who read of my woes!

Regards to all,

Sparky

 

[coley]

how hot is the water could the thermostat have failed in the past is the property in a hard water area if so it could be limescale problem.

Maybe just an idea

Coley

 

[TheArtfulDodger]

Hello, Coley:

Yes, we live in a very hard water area and we cannot stand water softners - so we have to suffer the consequences of that. In the past we had to have the cylinder descaled but this time we were fortunate in that it was simply the mixing valve. I don't think the bad valve was ever right because I could never change the temperature of the tap water, regardless of setting.

The new valve, despite assurances to the contrary by the installer, does allow me to change the temperature of the water at the tap! I enjoyed a wonderful shower, without worring about running out of hot water, this very afternoon!

Thanks again.

Sparky