hot water only works when heating on?

[G-Unit]

Hi... As the title says really.... The hot water just doesn't appear to work unless the heating is on at the same time.

Boiler is a Baxi Bermuda 552. A back boiler with an oldish gas fire on the front.

hot water cylinder is in a cupboard almost directly above the boiler/fire, and tanks are in the loft almost directly above that.

The programmer/timer is a Hortsmann H21.

It's basically always been like this, I've been using the immersion heater but this is obviously expensive and a good way to kill elements.

I'm a fairly competent DIYer but don't have much experience with this kind of stuff. I've helped move a Radiator and install an electric shower but that's about it with regards to plumbing really. Done a reasonable amount with electrical stuff though. Just looking for some ideas as to what might be the problem with this.

Thanks for reading!

 

[twgas]

have you checked there is some water in f&e tank (couple on inches above cold feed connection)

do you have any valves in flow or return, or a thermostat strapped to hw tank

 

[G-Unit]

have you checked there is some water in f&e tank (couple on inches above cold feed connection)

Yes. not recently, but I have looked in there and there is water. Exactly what level I'm not sure, I'll have a look tomorrow.

do you have any valves in flow or return, or a thermostat strapped to hw tank

There is a thermostat strapped to the tank that was fairly recently replaced (when the immersion element was done a few months ago). Of the pipes going into the side of the HW cylinder the lower one has a valve on it (I think anyway, a box with wires attached!), which I believe is the flow into the cylinder, with the upper pipe not seeming to have a valve.

Forgot to mention that there is a single pump accessible through a small cupboard next to the boiler, but I assumed this is for central heating purposes.

Thanks for taking the time to read, I appreciate it!

 

[spacethegas]

blocked cold feed ?

 

[Agile]

That box with wores is probably a motor valve and may have failed.

I dont see with your level of knowledge that you will be able to anything much about it.

You will probably have to call someone!

Tony

 

[G-Unit]

That box with wores is probably a motor valve and may have failed.

If this was the case, how come it works when the heating is on? Surely if the valve had failed and was stuck closed, it would never work at all? I thought it was probably a valve of some sort. I'll have a closer look later on.

I dont see with your level of knowledge that you will be able to anything much about it.

Well... If I had the knowledge I wouldn't be asking. Like I said, I'm not daft and if need be I will call someone, but I much prefer to learn to do things myself, or at the very least learn enough to know if any tradesman I have to call is trying to rip me off.

 

[Agile]

That box with wores is probably a motor valve and may have failed.

If this was the case, how come it works when the heating is on? Surely if the valve had failed and was stuck closed, it would never work at all? I thought it was probably a valve of some sort. I'll have a closer look later on.

I dont see with your level of knowledge that you will be able to anything much about it.

Well... If I had the knowledge I wouldn't be asking. Like I said, I'm not daft and if need be I will call someone, but I much prefer to learn to do things myself, or at the very least learn enough to know if any tradesman I have to call is trying to rip me off.

Oh dear!

I tell you what I suspect is wrong and then you argue against me even though you admit you know knothing about the subject. Clearly you think that you have much greater reasoning power than I do yet you can only visualise one failure mode!

You must think that everyone involved in heating is an uneducated plumber who left school at 14 and is bound to be very thick!

Then you talk about getting ripped off. If you choose someone who talks intelligently and outlines his charging basis then how can you get ripped off?

You seem to think that anyone who can do plumbing is automatically a cowboy!

I suggest you call British Gas rather than take your chance with anyone else!

Tony

 

[G-Unit]

Oh dear indeed!

I tell you what I suspect is wrong and then you argue against me even though you admit you know knothing about the subject.

No you didn't, you merely suggested something, and I simply responded with a question, for the sake of clarification, because as I understand it a valve pretty much either works, or doesn't. So either it works, and allows hot water to go through my cylinder, or it does not. If I'm mistaken, then please tell me so. That is why I asked a question on a DIY forum. I personally couldn't imagine what it could be besides a valve, but I don't know that because I'm not a plumber. I also did not dismiss your suggestion because I did say I'll have a closer look at it later on.

You must think that everyone involved in heating is an uneducated plumber who left school at 14 and is bound to be very thick!

And you must think that anyone who says good morning is launching into a personal attack against you.

Then you talk about getting ripped off. If you choose someone who talks intelligently and outlines his charging basis then how can you get ripped off?

So... not talking intelligently means someone is a cowboy? Telling me how much they'll charge in advance and/or how much for various parts tells me that them replacing part X was a reasonably logical thing, as opposed to something that makes no sense in light of the problem? I'm sure the truly successful con-artists are all very well spoken and convincing - and that applies to any field, not just plumbing.

You seem to think that anyone who can do plumbing is automatically a cowboy!

I said that where?

You appear to have decided I'm embarking on a personal attack on you for some reason. I have no idea why.

Take a chill pill. I don't need to get this sorted out now, or even this week. As I said, I don't know that much... but I am capable of learning, and I have time to do so. If my reasoning about the valve is incorrect, please tell me so & why.

 

[gas4you]

Well that told you Tony

OP assuming that the valve in question is a 2 port, pipe at either end, then the reason the water will get hot whilst ch is on, could be because the valve is stuck open or has been told to open by the cylinder thermostat.

The cylinder thermostat operates only the valve motor usually, then it is the motor opening the valve that operates a microswitch in the valve head and this in turn supply's the power to tell the boiler to fire.

So you could have a working motor but broken microswitch, very common fault.

IF you have a gravity HW system, then the wiring to the valve would be slightly different.

Visit the Honeywell site for good diagrams and info on wiring for heating systems.

 

[G-Unit]

The cylinder thermostat operates only the valve motor usually, then it is the motor opening the valve that operates a microswitch in the valve head and this in turn supply's the power to tell the boiler to fire.

I see... this makes sense

So you could have a working motor but broken microswitch, very common fault.

Right, I had a bit of a closer look at the zone valve and it appears it must have leaked at some point in the past, as there is a fair bit of lovely greenish corrosion around it. I've never had a problem with water from this valve though, and it is dry now... So maybe it leaked enough to knacker the electrical side of it at one time and someone fixed the leak but didn't fix the rest...

IF you have a gravity HW system, then the wiring to the valve would be slightly different.

I thought I had a gravity HW system (Large diameter pipes that appear to go straight from boiler up to the HW cylinder) But the pump next to the boiler appears to run when only the HW is 'on', as well as when CH is on. However boiler doesn't appear to fire when only hot water is on (though pump keeps running), which follows your suggestion about the microswitch....

I'll study the pipework a bit more tonight then...

Thank you very much for your response Dave, it was very helpful.

 

[Rico99]

G-Unit,

Sounds then llike you have fully pumped system with a 3-point valve.

Problem is most likely with this.

Had a similar thing in my own house. When calling for hot water the rads cam on aswell.

Changed the 3 port valve and problem solved. It may have been possible to just change the motor, but decided to replace the whole thing.

Rico

 

[G-Unit]

G-Unit,

Sounds then llike you have fully pumped system with a 3-point valve.

Problem is most likely with this.

Had a similar thing in my own house. When calling for hot water the rads cam on aswell.

Changed the 3 port valve and problem solved. It may have been possible to just change the motor, but decided to replace the whole thing.

Rico

Well, the valve in question only appears to be a 2-port one. one pipe in one side, and one pipe out the other. The Larger pipes (at a guess, around 30mm diameter) coming out of the boiler just seem to come out and go straight up through the ceiling to where the HW cylinder sits*, so don't appear to run through the pump (as I said, I'll study the pipes in more detail tonight).

*The Boiler/gas fire is at the bottom of the chimney, and the pipes come out the side. A previous owner has built a small plasterboard 'extension' on the side of the chimney downstairs that hides all the pipework. there is a small cupboard door on the side of this which gives access to the pump... so I can see various pipes but cannot easily see the whole length before they dissapear into the ceiling, because of the box built around them.

 

[gas4you]

Sounds like a standard gravity primary system. 1"/28mm pipes feed the indirect cylinder whilst 3/4"/22mm pipes off the boiler feed just the rads.

Your 2 port valve, I hope, is installed in the branch to/from the cylinder and not in the main flow or return pipes, other wise this would be dangerous.

 

[G-Unit]

Sounds like a standard gravity primary system. 1"/28mm pipes feed the indirect cylinder whilst 3/4"/22mm pipes off the boiler feed just the rads.

This appears to be the case... when fiddling with it tonight, the pump was only coming on with the CH. I have no idea why it appeared (or I thought) it was also coming on with just the HW as well yesterday... possibly me being confused I suppose

Your 2 port valve, I hope, is installed in the branch to/from the cylinder and not in the main flow or return pipes, other wise this would be dangerous.

Yes, it is installed in the branch to the cylinder...

Anyway, a bit of careful fiddling... and it seems that the Zone valve itself is seized. I managed to remove the motor from the valve, and have verified that the motor does turn when the cylinder thermostat is set higher than its temperature. I also found that if I activate the microswitch manually, the boiler fires.

I cannot move the valve at all, but I can easily bend the spring that I assume closes the valve when the motor isn't running. I guess this means that the valve has either actually jammed shut, or is jammed half-open (the cog on the motor appears to sit roughly halfway along the teeth when put back together).

So looks like I need a whole new valve... and need to drain the system to change it. hooray.

Thanks for all the posts so far people, all the information has been very helpful and has certainly brought me to a much better understanding of my system so far!

 

[G-Unit]

Well, last weekend I managed to replace the knackered valve successfully.

I got a Honeywell one for £31, and after taking the old one off I realised I'd need more pipe (was hoping to re-use the old pipe, but the new valve was a bit shorter than the old one)... Tried the plumbing trade place next to where I work, but they didn't have any offcuts of 28mm, so ended up having to buy 3 metres of 28mm copper pipe from B and Q, when I only needed about 5".. Fortunately I found some that was a bit dented here and there so I got it for £12, almost half price. I'll settle for that

After getting it all plumbed in, it seemed to be responding to the tank thermostat stat ok... but wasn't firing the boiler. after a bit of head scratching I realised the tank Thermostat was wired up backwards, so the valve was actually only opening if you turned the Stat down!

A quick bit of re-wiring later and it all is working as it should, and I haven't had the immersion heater on since the weekend and no-one has complained that there's no hot water yet.

Left some paper under all the joins to check for leaks and a couple of the fittings dripped a bit overnight on saturday, but tightened those up a little and it's all been dry since now.

So I've gone from knowing very little about it, to being pretty familiar with my CH/HW system, and have got the problem fixed for £44 in total. bargain.

Thanks for reading and posting, I appreciate you guys taking the time to reply, all the pointers were very helpful.