No Hot Water

emanresu · 22 Jun 2005

Having turned off the central heating for summer, we now have no hot water. It is tepid at best. It only heats up when the central heating is turned on. Does anyone have an idea what might be wrong or where I should look first?
Thanks...

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Hello again.
I noticed a similar question to mine in the forum, but it is for a combi boiler. I'm pretty certain mine isn't a combi boiler.
I asked my wife to give me make and model details over the phone and got this: iIdeal Classic LXRS & RF boiler size S260.

Hope that helps. Thanks for any help you can give.

MOD

please see 10a ...have done now. Thanks!

bathjobby · 23 Jun 2005

We can only try and help if you give some information. For example

Having turned off the central heating for summer

How ? Have you just turned the room thermostat down, have you turned the boiler thermostat down, turned of CH at the programmer ? does the programmer support separate CH and hot water, etc, etc, etc.

emanresu · 23 Jun 2005

Thanks for the reply bathjobby. When I say turned off, I mean turned off at the programmer. Must admit when I came across this site I jumped in with both feet. Can now tell you...
We have the standard indirect boiler system with pump feed. Programmer is a Drayton Tempus Three; supports CH and HW separately. When I turn on the CH the pump comes on. It doesn't come on when CH is off and HW is on. I am suspecting that the programmer needs replacing.

shoreman · 24 Jun 2005

hi if its a pumped system you may have a three way control valve which is stuck on the central heating system circuit . you will get radiators hot but nothing going to heat the hot water hardly. switch the system on and see how long the water takes to get to the tank it should be as fast as to the radiaters if not its the control valve which is u.s

emanresu · 24 Jun 2005

Hi shoreman. I've never noticed a problem with the hot water when I have the CH on; it can get piping hot if needed! Hopefully that means the valve is ok then?
If not, what does it look like and where would I find it? I've tried to find a diagram on the web showing more than just the ins & outs of the cylinder but no luck.
It confuses me, but perhaps I should draw and post my layout! It includes two square "boxes" which I guess are valaves of some description (they have a sprung lever that sits either at manual or automatic, from memory).

shoreman · 25 Jun 2005

hi i no this sounds condescending but its not ment to be.
the system is simple hot wter from the boiler is pumped to the indirect cylinder and heats the hot water supply so you are not getting heat to the tank , basics.
put the hot water only on and trace the system
1 is the pump working
2 if so the boiler water is trying to get to the tank to heat the hot water
3 is there a valve in the line from the pump to the hot water cylinder ( these are the pipes that go into the side of the indirect cyl flow being the top one and return the bottom) this valve is usually controlled by the tank thermostat situated on the tank itself which closes the supply to cylinder when the water gets to the desired temp.
4 if you find the valve manually open it useing the lever .
5 if when you open it the water is felt getting through and the water will heat the hot water system then there is a problem with the valve which could simply be the tank thermostat.
there is nothing special about the central heating circuit just think of the circulation as traffick flow and be logical , start at basics and trace the hot water flow with the system on hot water only ie boiler on heat supply ok , pump going ,where sould it go next ,to the tank to heat the hot water, whats in the line thats stopping it , can you feel the water go to a certain
point , whats stopping it reaching the tank.
when you find the fault it will be so obvious you will kick yourself for not being logical .

emanresu · 25 Jun 2005

Hi, not condescending at all just very well explained!
In my system the electrics all meet in one large junction box, so I could only see what is linked by opening it, but it is difficult to get to. Even the pipe work doesn't look totally logical; there is a thin pipe, with what I guess is a different type of valve (or something!), that links the top and bottom pipes coming out of the cylinder. My guess is that it is some sort of pressure relief system?
Anyway, with your description I have a much better idea of what most of it is doing. I've had the CH on this morning to give me some hot water. Once the pipes have cooled down a bit I'll go through the steps you explained.
Thanks a lot for your help.

kevplumb · 25 Jun 2005

3 port valve

ollski · 25 Jun 2005

kevplumb said:
3 port valve

Suspect 2 of these:

CopperCylinderMan · 25 Jun 2005

emanresu said:
It includes two square "boxes" which I guess are valaves of some description (they have a sprung lever that sits either at manual or automatic, from memory).

emanresu said:
It doesn't come on when CH is off and HW is on

does the square box (i think this is a motorised zone valve) (see previous post for picture) on the hot water section of your heating system operate when when you program HW only? if it does, but the pump still doesnt fire, it sounds like a faulty 'end switch' in the MZV - needs replaced.

If it doesnt operate, but you get things working when you manually open this valve, it could be your programmer or the motor in the MZV.

HTH

CCM

emanresu · 26 Jun 2005

Thanks for the pictures kevplumb and ollski. I cannot see a 3 port valve anywhere, and yes it looks like I have 2 MZVs.
Here is a (badly drawn) diagram of what I have, not to scale obviously...

The red box is the pump, the two green boxes are the MZVs, on the cylinder I have shown the immersion and the thermostat, the yellow end piece has something that could be turned by a screwdriver inside it, and the blue thing jutting out of the thin pipe ends with something that looks like it could be turned with a small ring spanner. I haven't shown any of the electrics.
CCM, when I turn on the CH the programmer clicks and the pump comes on. I get hot water and hot radiators. When I turn the CH off, I can hear an MZV rewinding; I think it is the left hand one.
When I turn on the HW the programmer clicks but the pump does *not* come on. Nothing rewinds when I turn the HW off. Nothing happens when I push the lever to manual, I assume that is because the pump isn't on?
On pushing the lever on the MZVs to manual, they both return to automatic - though sometimes the right hand one sticks and doesn't return. Neither lever moves when I turn on CH or HW.
Thanks all, for your help on this...

ChrisR · 26 Jun 2005

I'm assuming you have the valves with the metal case as shown above.

As you've described, the HW valve isn't opening enough to close the switch inside which starts the boiler and pump. If you shove the lever of the right hand valve (HW), fast to the MAN position so the insides carry on past, you'll probably hear it click twice, turning the pump on and off. You're opening the valve against a spring, you should hear/feel it shut again. The signal from the programmer via the cylinder thermostat is meant to open the valve far enough to switch the P & B on, but that isn't happening.

So you have to turn the CH on to get the boiler on.

The HW valve (on the right, connected to the cylinder) is either stuck part way open (sticks sometimes?) or it always opens but not far enough to close the switch inside to bring the P&B on. In its unpowered state, you should feel resistance when you open it. If you don't, it's stuck.

The actuators/heads/silver bits can fail to go far enough, or have bust switches inside, or the valve part (brass) underneath can be half seized and not letting the actuator work. Or the motor inside can be bust (commonest fault), or the programmer or cylinder stat could be faulty.

The with HW on at the programmer the cylinder stat should click if you turn it up and down (water hottish), and you should be able to tell if the motor in the HW valve is moving (they take 20 secs or so to open, much less to close).

emanresu · 26 Jun 2005

Thanks Chris.

If you shove the lever of the right hand valve (HW), fast to the MAN position so the insides carry on past, you'll probably hear it click twice

On the good, and newer, left hand valve I heard the two clicks. On the right hand valve I didn't, and it tooker slightly longer to return.
I did this unpowered and felt resistance in both.
These are Honeywell valves; the newer one has F6 - 9816 stamped on it. Is it easy to replace or does it involve cutting pipes?

Also, with HW powered, I turned the thermostat. Thought I heard one click as I turned it up, but otherwise not really. Didn't hear motor on MZV but don't hear it on newer one either. Only notice rewinding sound when unpowered again.

Thanks again...

PS Is your location correct!!? That must be why you are up so late

ollski · 26 Jun 2005

emanresu said:
Thanks Chris.

If you shove the lever of the right hand valve (HW), fast to the MAN position so the insides carry on past, you'll probably hear it click twice

Click to expand...

On the good, and newer, left hand valve I heard the two clicks. On the right hand valve I didn't, and it tooker slightly longer to return.
I did this unpowered and felt resistance in both.
These are Honeywell valves; the newer one has F6 - 9816 stamped on it. Is it easy to replace or does it involve cutting pipes?

Also, with HW powered, I turned the thermostat. Thought I heard one click as I turned it up, but otherwise not really. Didn't hear motor on MZV but don't hear it on newer one either. Only notice rewinding sound when unpowered again.

Thanks again...

PS Is your location correct!!? That must be why you are up so late

The hot water valve is knackered...hopefully just the motor. Call for hot water on the programmer and push the arm a little more after it has moved across, if it fires the pump after a few seconds then your motor is gone, if not then probably your microswitches which means new head. If the valve cover has a little dimple on it a head change is simple, if not it means bunging the system.

emanresu · 26 Jun 2005

I've never seen the arms move on either valve, they just stay on Auto. However, I turned HW on and then pushed arm over to Man Open. Held for over 20 seconds but nothing happened.

Now when I turn off HW I can hear rewinding from valve box. Wasn't happening before, but has done since I tried the fast pushes (see earlier).

Not sure about the dimples. There's two to the right of "Auto" on the top. The casing looks like it will slide off; I think I felt a screw holding it underneath which I'll check on tomorrow.

Ta Ollski...

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