TRV for hot water temp - good or bad?

[-Sean-]

I'm having some problems with my central heating & hot water system and I think I need to understand how it works before trying to fix it but I'm scratching my head. Any help would be welcome.

I have a standard boiler (non-combi) and copper cylinder. In the airing cupboard the feed to the cylinder seems to be via a Drayton Thermostatic Radiator Valve with a thermocouple sticking out of it and going to the side of the tank. There's an isolator type valve too, a plumber who came round to fix a burst pipe said it's a diverter or bypass valve (can't remember) and said it was open but should be closed so he closed it. There is a two port valve that I think controls flow to the radiators and a digital programmer and analog room thermostat downstairs.

The problems we get are:

- heating doesn't come on unless hot water is switched on too (on timer)
- sometimes upstairs radiators get hot when hot water only switched on
- sometimes noisy (flow of water, not knocking or banging)
- I think pump runs all the time hot water is on
- Sometimes hot water gets too hot but this has been better now I turned boiler down after the winter
- Room that airing cupboard is in gets really hot, the pipes do run under the floor however.

Should the diverter valve be closed as the plumber says, as surely then when the TRV closes then the pump will not be able to circulate water as the flow will be blocked? If it needs to be open how do I know how much?

Untitled

• -Sean-
• 11 Apr 2011
• 1

Untitled

• -Sean-
• 11 Apr 2011
• 1

 

[Agile]

Did he close the red handled valve?

Tony

 

[misterdubya]

Drayton Thermostatic Radiator Valve with a thermocouple sticking out of it and going to the side of the tank.

Thats a 'tap-stat'.

The red handled valve is the system bypass and should not be fully closed.

Mr. W.

 

[bengasman]

It sounds like your controls are not working properly. Judging by the looks, it was not a very sophisticated design in the first place.
I doubt if this is something you can do yourself if you want it all to work as it should,

 

[oss]

I think the controls are working as designed[rooms stat controlling the heating].the rad stat[ if working] is adjustable[water too hot].the red handled bypass valve needs to be open[try half way].the upstairs rads could be the 2 way valve passing slightly or conduction through the return pipework.The pump will have a speed control on it try turning it down[a pump should run at the slowest speed that the system will work at.] The best way to up grade the system would be to install a 3 way valve controlling the hot water off a cylinder stat.

 

[misterdubya]

The best way to up grade the system would be to install a 3 way valve controlling the hot water off a cylinder stat.

Or just plumb in a zone valve where the tap stat is, and wire in an 'S' Plan with a cylinder stat.

Mr. W.

 

[-Sean-]

Thanks All.

Tony - yes it was the red-handled valve he closed. My father thinks it should be open at least a bit so I have released it a little now to allow some flow. Not sure how to adjust it more scientifically though!

Mr. W - thanks, googling 'Tap-Stat' got me some info on the Drayton valve that explains it a bit. The datasheet shows it on the bottom of the tank on the 'primary return'. Mines on the top, does that matter? Does it matter which way water flows through the cylinder coil, bottom to top or top to bottom?

I am thinking fitting a mid-position or zone valve and electric tank stat would be a good idea as I guess everything would work more effectively and efficiently. I suppose I could see if the existing valve works, if so go S-plan with an extra 2 port valve. If not go Y-plan with a new 3 port (more work). Should the cylinder feed be in 22mm if I redo it or is the 15mm ok?

Thanks

 

[JohnD]

the tapstat has a fine flexible pipe (it looks like a cable) that goes to the sensing bulb. Where is this bulb?

is the flexible pipe kinked or damaged?

 

[-Sean-]

The fine copper tube goes round in a loop (doesn't look kinked or damaged) then into the side of the cylinder. It's covered with yellow tape so I'll have to remove that to see better - I'll have a go later. I can feel something underneath and when I press a bit it moves in. It makes me think, if the sensor is not held tightly against the side of the cylinder I suppose it won't work accurately so maybe that is part of my problem.