Heating but no hot water

[alastairpearce]

Hello

New to this forum - I've got a problem with my hot water system, and try as I might I simply can't fathom what the problem could be.

Firstly, details of the system:
Ideal Classic boiler
Albion indirect hot water cylinder
Honeywell 2 port motorised valve (model V4043)
Grundfos selectric pump
Honywell control unit

Here's the problem - when I activate hot water only on the control unit, the boiler fires and the flow pipe from the boiler to the heat exchanger in the indirect water cylinder gets hot. However, the water cylinder doesn't heat up and the water coming out of the hot water taps is only lukewarm.

When I select heating as well as hot water the radiators get hot (all radiators get hot right to the top).

Selecting heating only on the control unit doesn't fire the boiler, so I assume I can only have heating with hot water. This has been the case since I moved into my house over a year ago.

On reading other posts on these forums, the only two problems I can think of are either a faulty motorised valve, although I can't think why this would be the problem if the feed pipe to the heat exchanger in the cylinder is hot.

The other issue is potentially and air lock/blockage somewhere in the system? I have opened the drain tap in the return pipe to the boiler from the cylinder, and hot water flowed through the pipe which would suggest there is no air in the heat exchanger.

Therefore I am totally stumped on where the potential air lock could be? The cylinder must be full of water, because lukewarm water is coming out of the hot taps.

I'm a novice with heating systems, and the only knowledge I have is what I have gleaned from reading these forums.

If anyone can suggest how to solve this problem, I would be most grateful. I've included some photos above of my hot water cylinder, 2 port valve and cylinder thermostat, if these are of any use. I can't make head or tail of the pipes coming in and out of the cylinder (like i say I am a novice.

Thanks

Alastair

 

[WHPES]

Have you bled the cylinder coil?

Looks like a very old fashioned set up originally from a gravity system. Suggest you upgrate to fully pumped Y plan or S plan.

 

[alastairpearce]

Yes i've bled the cylinder coil.

 

[Chrisgy]

Could be the thermostatic cylinder control the one that looks like a rad valve what's that set at? And how long are you leaving it on for to heat tank

 

[alastairpearce]

The thermostatic cylinder control is set to maximum, and I have had the hot water on constantly but no heat in the tank.

 

[Gray0689]

The thermostatic cylinder control is set to maximum, and I have had the hot water on constantly but no heat in the tank.

Try taking the head off the cylinder control it could be stuck nearly closed

 

[Spike295]

Can you feel the pipe is hot going into the coil & hot coming back out of the bottom tapping, or is the heat not going into the coil & going straight down the bypass.

 

[Spike295]

Try taking the head off the cylinder control it could be stuck nearly closed

As said above, undo the screw in the black ring under the white head & pull off. Check to see if the pin underneath the white head is free to move in & spring out. A gentle tap will help.

 

[alastairpearce]

Can you feel the pipe is hot going into the coil & hot coming back out of the bottom tapping, or is the heat not going into the coil & going straight down the bypass.

Yes, the pipe going into the coil is hot, and when I bled the coil in the cylinder, the water coming out of the bottom tap was hot also.

 

[alastairpearce]

Try taking the head off the cylinder control it could be stuck nearly closed

I'll try this, although this problem has only recently occured following normal operation for over a year, and the thermostatic valve hasn't been touched in all the time the hot water has been operating normally.

 

[Spike295]

How long ago since you bled it & any difference in water temp since you have!

 

[Spike295]

I'll try this, although this problem has only recently occured following normal operation for over a year, and the thermostatic valve hasn't been touched in all the time the hot water has been operating normally.

They tend to stick & slowly close down after time, not releasing to fully open, press it down a few times & see if it springs back up. The flat of a screwdriver will aid in pushing it down.

 

[vaughan]

I think some1 here once told me even if the pin springs back up and down does not mean that its not still stuck closed.
But defo worth trying to free it as already suggested.

 

[Spike295]

I think some1 here once told me even if the pin springs back up and down does not mean that its not still stuck closed.
But defo worth trying to free it as already suggested.

Very true, but in this case he got some heat passing thru so if it is the pin, its only partially shut & has a pretty good chance of freeing up.

 

[alastairpearce]

UPDATE: Managed to get the thermostatic control white knob off, initially tried pressing down the pin inside but it was definitely stiff and I couldn't depress any further. Gave it a few sharp taps with the handle of a screwdriver, and it was springy after that, and I could freely push it down and it would spring back up. Following this there was a definite whooshing sound within the system, and now both the flow and return pipes in the coil are hot.

Too early to tell if the cylinder is heating up fully, but fingers crossed this is the solution to the problem!

 

[Gray0689]

Hope all sorted now glad we could help

 

[Spike295]

Sounds pretty positive.

 

[vaughan]

Does sound like it has helped.

 

[alastairpearce]

Yes thanks, the hot water was piping hot this morning.

Thanks for your help once again.

 

[Gray0689]

Welcome