Hot Water Only But 1 Rad Heats Up

[camel307]

I have recently switched my timer to hot water only. However, one heater still warms up!!

Admittedly it does not warm up to same temperature as if heating set to being on but none the less it is warm.

Standard gravity fed system with hot water cylinder in airing cupboard and rad that warms is rad closest to airing cupboard (same room).

Any ideas? Help much appreciated.

Thanks people

 

[holty]

without looking id guess you have what is called reverse circulation.best way to diagnose, is start from cold. feel which rad pipe on the rad gets hot first on dhw.then turn on the ch.if the hottest goes cold and vice a versa.then thats a good sign of your problem

 

[camel307]

Thanks

I dont think this is the issue though as i only noticed this happening this week.

Almost certain it was not warming up about a month ago

Could it be the directional control valve. If so is the only solution to just change it or can you strip them down and have a look?

Also, how do you change these things?? Do u need to drain system etc..
Thanks

 

[holty]

a little bit more info wouldnt go amiss.you said you recently just changed to hot water.yet you only noticed a problem in a week.yet recently to you was a month ago.a bit more of what was changed and your system.might help.was my fault for jumping head first to your diagnosis.been a long day.i should of found out what your layout was and wasnt first.but the good info you give will help most to give you a better answer.

 

[camel307]

I changed to hot water only on 13/04/10 at 8:36am. I noticed rad warming up on 20/05/10 at 9:45am.

If you dont know...dont worry

 

[D_Hailsham]

Standard gravity fed system with hot water cylinder in airing cupboard and rad that warms is rad closest to airing cupboard (same room).

What do you mean by a standard gravity fed system?

 

[camel307]

bog standard system - no extra complexities.

 

[45yearsagasman]

When you say bog standard,are there any motorised valves in the airing cupboard? You really need to describe your system properly.

 

[D_Hailsham]

When you say bog standard,are there any motorised valves in the airing cupboard? You really need to describe your system properly.

It's like pulling teeth.




























































Slow and painful.

 

[JohnD]

some photos showing the pipes around the boiler and cylinder, pump, and any valves or other control would make it possible to help

//www.diynot.com/forums/viewtopic.php?t=129539

Have you got any thermostatic radiator valves?

if you turn off the warm rad, does a different one heat up?

 

[camel307]

sorry guys I am no expert......

My system is a pumped system. Boiler downstairs that links to hot water cylinder but there is a motorised valve that has an input and two outputs (one to cylinder and one to rads) before supply from boiler reaches cylinder.

Rad in bedroom, closest to boiler, heats up. If i have heating on long enough the next rad also heats up but only very slighly. If i shut off 1st rad 2nd one warms up more.

I suspect it is this motorised valve but before buying a new one I would like to confirm this...just stuck for how to achieve this?

Thanks everyone and sorry if i am not explaining properly.

 

[JohnD]

some photos showing the pipes around the boiler and cylinder, pump, and any valves or other control would make it possible to help

//www.diynot.com/forums/viewtopic.php?t=129539

Have you got any thermostatic radiator valves?

if you turn off the warm rad, does a different one heat up?

 

[D_Hailsham]

My system is a pumped system. Boiler downstairs that links to hot water cylinder but there is a motorised valve that has an input and two outputs (one to cylinder and one to rads) before supply from boiler reaches cylinder.

Got there - at last.

You have what is called a Y Plan system, so called because of the motorised valve which has one input and two outputs. This valve can take up three positions: HW only, CH only or both CH and HW (mid-position).

Rad in bedroom, closest to boiler, heats up. If i have heating on long enough the next rad also heats up but only very slightly. If I shut off 1st rad 2nd one warms up more.

Holty (second post) suggested reverse circulation, but you rejected this (third post) on the basis that you only noticed it happening this week. However you say in your first post: I have recently switched my timer to hot water only.

If you have only noticed the problem since you turned the heating off, then reverse circulation is more likely to be the problem. After all, when the central heating is on, you will be more concerned if a radiator does not heat up.

Carry out Holty's test first.

P.S. - A "gravity" system can mean two different things. To the pro it means a system with pumped heating and gravity circulation hot water. However many lay people call a system with header tanks in the loft a "gravity" system; but the pro refers to this as an "open vent" system.

 

[combispecialist]

simple test......system completely cold,turn hot water on...does flow pipe to radiators from diverter valve get hot????if it does the diverter is passing,if not ure system is backeeding.