new better clearer photos posted see link below

[Simon]

is the third time i've tried to post this link. third time lucky!!!!!!!!!!!

[Roger Mills]

OK, that tells us a bit more.

One thing which may be significant is the gate valve which can be seen in photos 23 and 29 (among others). The pipe in which that valve is fitted appears to be some sort of by-pass across the cylinder's heating coil - maybe so as to provide a flow path when the TRV-like valve closes. How open or closed is that gate valve? (Count the number of turns required to close it from the current position, and then the turns required to open it fully from closed, to give a measure of its current state). If fully open, it provides a dead short for the coil - with the result that nearly all the primary water will go down the by-pass and very little through the coil - which could well explain your problem.

If it's open a long way (or fully open even) try running with it only open a little - maybe half a turn from closed) and see what happens. If you *need* a by-pass at all - and you may or may not depending on the requirements of the boiler and on how the system 'controls' are configured - you'd be far better off with a spring-loaded auto by-pass valve which only opens when it needs to, rather than a manual gate valve.

[chris French]

I'm not sure if we ever heard if the tank was actually getting hot or not (or was there some other problem after the tank with the HW) - a quick hand test on the metal of the tank will confirm. (near the top of the HW tank obviously)

If it isn't then the capillary valve would seem like a prime candidate for failure of some sort (either valve or capillary tube/sensor). Presumably they are like a TRV inside. If you remove the top (ours has a knurled ring at the base of the body you unscrew) then presumably it just leaves the valve open. That would be my first try.

I'm not sure about how they actually work, but assuming they have a pin operated by the capillary senor, this could be stuck like the ones in TRV's do.

[Terry Fields]

The photos strongly suggest you have the same sort of heating system that we've just left behind.

This is a boiler that heats primary water (usually fed by a jockey tank somewhere above the hot water tank) that circulates through a heating coil in the HWT to provide domestic hot water, and via a gate valve to the radiator system.

Helpfully, the photos show that this valve is marked 'heating system' on the wall just above it. It's a racing cert that all your radiators have thermostatic valves on them.

Normally, primary water from the boiler will circulate through the heating coil in the HWT until the capillary valve (the one with the thin pipe going to the sensor strapped to the tank) shuts down at the temperature set by control knob.

Also, if the heating gate valve is opened, primary water will circulate through the radiators until their TRVs shut.

With both the capillary valve and central heating shut off due to reaching the set temperatures, the pump will still be running as it is controlled by a timer. In this case the pump must not run in the 'stalled' condition, it needs to pump water continuously. This is obtained through a bypass controlled by another gate valve, almost certainly the one on the vertical pipe running towards the top of the HWT.

As others have pointed out, if the bypass valve is too 'open' water will preferentially pass through it rather than the heating coil in the HWT, leading to a lack of domestic hot water.

Another problem is a fault with the capillary valve; either it is stuck shut and not allowing primary to flow through the heating coil, or the capillary or sensor is faulty leading to the valve not opening.

Try this sequence of fault-finding:

Unscrew the knurled ring holding the capillary valve head to the body, and gently place to one side. If there is a plunger pin on the valve body, gently try pulling it upwards with pair of pliers to see if it is free. Use a folded rag to avoid marking the pin. Wick some WD40 down the shaft of the pin.

If there is no pin in sight, leave the valve head off.

Now shut the 'heating system' valve, ensure the boiler thermostat is nat about two-thirds of maximum.

Turn on the system at the timer/control clock.

If the pipe both sides of the capillary valve gets hot, then water will be flowing through it and the heating coil, and hopefully heating the DHW. If there is no or little flow of hot water past the capillary valve after say ten minutes (feel the pipes as far away from it as possible), shut the gate valve on the vertical pipe, and then open half-a turn. See if this makes any difference to the water hopefully flowing past the capillary valve.

With the system running, the bypass valve almost shut, yet no hot water flowing past the capillary valve, a fault in the body of the latter is almost certain, suggesting replacement is necessary.

If hot water is passing the capillary valve, screw the valve head back on and set it at maximum. Wait some minutes to see if hot water is still passing through it; after ten or fifteen minutes the water in the HWT should be heating up. If so, turn the setting to minimum. If not, there may be a fault in the valve head, again suggesting replacement is necessary.

Now. listening to the heating pump, shut the bypass gate valve. The speed of the motor may increase as it is now doing nothing; crack open the valve slowly until the speed of the motor drops to almost 'normal' (when it is pumping hard). Although water will be bypassing the heating coil, it should nevertheless be a limited amount. This water is not 'lost', it is merely going back the boiler, but you only need enough of it to keep the pump happy when it has noting else to do.

Hopefully this will have either shown up faults in the capillary valve, and set the bypass valve to a reasonable setting. Unfortunately, gate valves can get sludged up and although apparently shut, may in reality still be partially open, confusing the picture.

Nevertheless, give this a try and see what happens - it might get the system working properly, or at least give some pointers to where the fault might lie.

If all is well, you can try fine-tuning the system by e.g. increasing the boiler thermostat setting (quicker heating by the CH circuit) and the setting on the capillary valve to give the temperature you want.

Good luck!

TF

[Simon]

many thanks for your reply. the gate valve directly above the TRV-like valve in photo 23 was fully open. It took seven full turns to make it fully closed so I have turned it six turns and put on the gas boiler to see what happens. I will post and let you know.

btw - to clarify: the gas boiler has not been heating the water above tepid. I had the gas boiler on max for one hour and the hot water was barely warmed at all. Because of this I have been using the electric heater to heat the water, which it does but it takes about 90 mins to make a hot bath, which costs a fortune. When the electric heater has been left on accidentally, the water boils merrily, filling the attic room with condensation. For this reason, I am fairly sure that there is no temperature sensor cut-off system in place for hot water tank.

many thanks for your help. i'll post in about an hour to let you know how having the manual gate valve nearly closed affected the HW temp.

Simon

[Simon]

hi TF,

Many thanks for your detailed answer. I really appreciate your help.

I apologise that I have to ask this, but I really don't have your technical expertise or understanding. In your note you outline various different valves and what they do and how their settings might be affecting the working of the system, but from reading your answer I am not sure which valve is which. Could you indicate which photo/s the valve/s are in?

i think the "bypass valve" you speak of is the same as the "manual gate valve" that Roger mentions in his reply. It was fully open and so I have almost closed it and put the boiler on to see if that helps the gas boiler to heat the DHW.

I presume that the "capillary valve" you refer to is the TRV lookalike? What is the optimum setting for this valve?

i'll post in about an hour to let you know if closing the manual gate valve/bypass valve made any difference.

many thanks for your help.

Simon

[Terry Fields]

You have two gates valves.

One is a bypass for the heating coil in the hot water tank. It's function is to give the pump soemthing to do when all the other valves in the system have shut. It is the one shown in photos 2 and 8 and is on the vertical pipe that leads towards the top of the hot water tank.

It needs to be cracked open just a little, probably half-a-turn might be too much, but you have to start somewhere.

The other gate valve is the one that lets hot water circulate to the radiators. It is shown in photos 3, 4, 5, 6 and has the words 'heating valve' on the wall above it. This needs to be fully open if you want the radiators on, or fully shut if you don't. For this experiment, keep it closed.

Yes.

You set this to give the temperaure you want of the water from the hot water taps. At the moment the valve isn't doing anything as the bypass gate-valve is fully open and so there is very little flow of primary water from the boiler through the heating coil. As a start, set this TRV look-alike at mid-value. If the bypass gate-valve trick works and the water in the tank gets hotter, then you can experiment to get a temperature to suit you.

OK.

You appear to have a fault with the immersion heater thermostat, but let's deal with one issue at a time. If the problems with the valve settings can be overcome, you might not need the immdersion heater 'til spring.

You're welcome. I hope it all works for you.

TF

[John]

Bear in mind that a thermostat for an immersion heater only costs about £8.

New ones trip out if the thermostat contacts weld together and the water gets dangerously hot.

[Simon]

Hi Terry,

Many thanks for your messages. I actually think I am beginning to understand the system!!!

Sorry I didn't post up the results as I said I would. I went to test the bypass valve only for my son to put the electric water heater on halfway through the test, so the water got hotter but i didn't know why. I will try tomorrow when the water is cold and there are no teenagers walking around the house randomly turning stuff on ;-)

btw - you mention that the Heating Valve needs to be either fully on (if the radiators are on) or fully off (if the radiators are off). Do I understand you correctly if i take it to mean that the Heating Valve cannot be partially open at all? The Heating Valve has to be either fully closed or fully open, nothing inbetween?

If it was left, say, half open, what would be the ramifications?

If the Heating Valve is kept closed and the radiators kept off would this actually help the gas boiler to heat the water quicker/ hotter? I ask this as we rarely use/need the radiators at all (we live in Devon, so it's v.mild here), but having the gas boiler actually heat the tap/ bath water would be a real boon!

But are their any downsides/ramifications/considerations to leaving the radiators off all the time and the HV closed?

Many thanks again.

Simon

[chris French]

The latter issue of the water in the tank boiling when using the immersion heater is almost certainly due to a failed thermostat controlling the immersion heater (this is all separate from the temp control relating to heating it via the boiler). The thermostat is cheap (about a tenner) and easily replaced.

This page show what is involved:

Re the problem of heating via the boiler, I suspect the culprit might be the TRV-a-lke/Tapstat . It sounds to me as if it either has got stuck in a mostly closed position. Radiator TRV's do this qiute often.

I guess they are basically the same inside. If you remove the head of the valve - at the base of the white body of the top of the valve should be a metal ring. This can be unscrewed (might be tight and need pliers/wrench to start) and then the body removed. Inside you should see a pin sticking up. This pin can stick - typically with the valve closed so stopping it operating. You should be able to push it up and down. f you can't you can use pliers to wiggle it or gently tap it to free it up. If it will move freely than leave the top off this should leave it open, and then hopefully then water in the tank will heat up

[Terry Fields]

Teenagers are rather like that :-(

For the next test either tell them not to turn the immersion heater on, or tell them anyway and also put some sticky tape or a post-it note over the switch.

Bear in mind you might have more than one fault in the system.

To try and find one fault at a time, try this scheme:

[1] Shut the 'Heating Valve' gate-valve. This shuts off the supply to the radiators, so the heated water from the boiler has nowhere else to go but to the heating coil/bypass gate-valve. It takes the whole issue of the central heating out of the fault-finding loop.

Now, we don't know if the boiler is producing enough water at the right temperature - it too could have a failed thermostat. However, we have to start somewhere.

[2] set this boiler stat at two-thirds of its Max setting. [3] shut the bypass gate valve, then open it half a turn. [4] open the TRV-like capillary valve fully. This valve may be faulty, but this is an easy place to start. [5] Put your hand on the hot water tank near the top and see how warm it is. [6] Turn the boiler on. [6] After about 15 minutes, feel the pipe below the bypass gate-valve, it should be warm to hot. Then feel the pipe above the bypass gate-valve, hopefully it won't be so warm but if it isn't, don't worry at this stage. Feel the hot water tank in the same place as last time. Is there any difference yet? If the hot water tank is getting warmer, well and good. In any case, let the system run for a total of 30 minutes or so. [7] After 30 minutes, you should be in one of two positions: a) the hot water tank is heating up significantly or b) there is no real change.

If the former is the case, then you're on the right track, and skip the paragraph below.

If the latter, then gently and carefully unscrew the head of the TRV-like capillary valve. Does the body of the valve have a central pin protruding it, underneath the head that you've just removed? If it hasn't, ignore the next step. If it has, then with a pair of pliers and protected by a rag or several folds of paper, genty pull the pin up.

Leave the system running for another 30 minutes, for a total of one hour. This is enough time to heat a tank of hot water, so after this span of time, you should have the following results:

1) TRV-like caplliary valve in place: water either heats up or it doesn't. Please report this result. 2) TRV-like capillary valve head removed (and pin pulled up if there is one): water either heats up or it doesn't. Please report this result.

At his point domestice needs suggest you replace the TRV-like capillary valve and temporarily go back to whatever system you were using to obtain hot water. Depending on the results of these tests, there may be more to do - but do these first.

There is no benefit to having the Heating Valve gate-valve partially open. The system should be (but clearly isn't) balanced to share the water-heating and radiator heating with this valve fully open. Fiddling with this at this time will only confuse the issues - we need to make progress in getting hot water. I suspect the central heating part will be OK, but that's for later.

A bodged system with potential faults all confusing the picture. Normally, you'd have this fully open or fully shut.

That's the point we're trying to get you to. Playing with the central heating at this point will only confuse the issues.

The rooms won't be so warm! Also, the TRVs can stick shut - but if you've got the hot water working by this time and you need central heating, it's just a case of taking the head off and freeing up the pin - although this isn't the only failure mechanism. My advice: ignore the central heating for now. Get the hot water working.

Lets us know the results of the tests.

TF

[Terry Fields]

oops...

That should read "..gently and carefully unscrew the knurled collar under the head of theTRV-like capillary valve, and gently remove the valve head - it will have the delicate capillary pipe attached".

TF

[<me9]

Gate valves are notoriously unreliable. A possible complication is that it doesn't shut off. feel a foot or so of each side when it is off to see if it is sealing. (it shouldn't need to be off for hot water anyway, so shouldn't matter).

Are you in a hard or soft water area?

[Terry Fields]

I did mention this problem in a previous post, but the OP has to start somewhere in sorting out his hot-water problems, so put it towards the back burner for now.

The OP is in Devon, so I guess it's a soft-water area.

TF

[docholliday]

At this time of year, when heating requirements are relatively low and the radiator TRVs will be nearly closed, there shouldn't be much effect. If/when the weather gets colder, there will come a point where the valve is restricting the flow too much and the system will fail to keep the rooms at the desired temperature.

Mike

[Simon]

Hi,

I did the test with the settings as suggested by Terry: ie, bypass valve a quarter-turn open, heating valve completely closed, gas boiler thermostat set on 4 (max is 5), TRV-like capillary valve fully open). After half an hour the tank was slightly warmer (you could feel it was a bit warmer but not much and certainly not near "hot"). The pipe going from the tank to the TRV capillary valve was somewhere between "no difference" to maybe "slightly warm"), but the pipe going from the TRV capillary valve off to the top tank and the rest of the system was very hot (too hot to touch). Is this the way it should be?

After 30 mins I ran the bathwater and the water was warm but not enough for a bath. After 90 mins I ran the bath and it was running too hot to touch and there was enough for a bath.

So... yippee!!! Many many thanks Terry! This is the first time we have ever been able to have a hot bath without having the electric heater on for more than an hour (usually 90mins min). Just this on its own will save me a fortune and make life so much easier. All i need to do now is try the gas boiler thermostat on diff settings for diff lengths of time to find the optimum setting for water temperature, time to heat, and units used etc.

But... from the above, is this HW system now working well or should it be better?

btw - When I say "gas boiler thermostat" set on 4" I presumed you meant the actual dial-setting on the boiler itself, and not something on the water tank or associated pipework. Is this right? I couldn't see anything else on the tank that could be adjusted and so I presumed that the dial setting on the boiler was what you meant.

Because of the success of the above test I didn't remove the top of the TRV-like capillary valve and see if the pin was stuck in a partially closed position, from the above do you think this is necessary or a still a good idea?

Because the water can reach boiling in the tank I guess it means there is a failed thermostat that needs replacing as you say, and this is something I should look at (even though i presume limiting the heat is purely a safety measure, and is not something that is done for the efficiency or otherwise of the system).

@B Trends - I live in a hard water area (I can tell from the build-up in the kettle, the taps etc, and how hard it is to get up decent suds for washing). I had thought about this possibly being part of the problem and could see how limescale could serious affect the efficiency of a CH/ DHW system. One solution I looked at was Scalewatcher

looked good but expensive (=A3150ish). What do you think about the cost/benefits of these kind of limescale removal systems? Are they worth it? Is it applicable to my situation?

When we move into winter and we want to have the radiators on for at least part of the day, will it be okay to switch between having the heating valve fully open to take the heat of the gas boiler to the radiators, and then close it fully to heat the water for a bath, and then after the bath to open the heating valve again to heat the radiators, or could this cause problems? Is it okay to simply switch between fully open and fully closed in this fashion?

Once again, many thanks for all your help. Any further advice that could help is gratefully received.

Simon

ps - i have ordered R.D.Treloar's "Plumbing: Heating & Gas Installations" to get a better overall understanding of how these systems should be set-up and should work. Supposedly it's the best one for the layman. It's on its way and I'm really looking forward to it!

[Terry Fields]

I'm extremely pleased you have got this far, and hopefully (someone) enjoyed a bath!

I'm not sure from the above description exactly what's heppening, but that's my fault.

You may have the bypass gate valve too far shut - try opening it to half a turn. It lets water through the bypass, but you need some to keep the pump happy.

No, no, no...

Leave the boiler thermostat setting where it is for now. The boiler is designed to run to its own settings - that's why you have control valves such as the TRV-like capillary valve and the TRVs on the radiator. Trying to run the whole system from the boiler is simply not the way to go - let each part it do its own job.

You control the temperature of the water delivered to the hot water taps (domestic hot water or DHW) via the TRV-like capillary valve only.

I suggested setting it on 'max' as an initial setting. Clearly it's too hot - possibly dangerously so. On the one in the system I used to have, the difference between setting no. 4 and setting no. 5 (out of

8) was the difference between hot water and very hot water.

I suggest you now try a setting about half-way as a start, and then experiment over the next few days to give you the DHW at the temperature you want. This will be a major milestone in getting your system running properly.

Difficult to say, but you do need to get the DHW temperature down to something more reasonable (hot but not very hot....you'll need to decide for yourself).

Yes, it was the setting on the boiler thermostat.

Yes, that's right.

It's not necessary. What I suggested was an experiment in case the DHW wasn't heating up at all. Clearly this isn't the case and your TRV-like capillary valve appears to be working fine - except that it just could be stuck open. However, if you can control the temperature of the DHW by adjusting it as mentioned above, that rules out another problem.

I take it you mean when the immersion is on. Hopefully you won't need it now 'til Spring.

Replacing an immersion heater thermostat is a straightforward job if one knows what one is doing. You could ask the question in a separate thread to get more knowledgeable people than myself to offer more informed comment.

I'm sorry, I couldn't advise on that. You might like to ask a seperate question to get informed comment from people who have installed and used these. I would suggest not rushing out to spend big money yet as although the DHW is on its way to working properly things have yet to be fine-tuned.

When winter strikes, or you just feel cold, put the system on and open the Heating Valve gate-valve fully. The flow of hot primary water from the boiler will be shared by both the DHW and CH circuits, so it will take longer to get a tankful of hot water and longer for the radiators to heat up fully. However, if you have set the TRV-like capillary valve to give you the DHW temperature you want, and the TRVs on the radiators to give the room temperatures you want, then these various valves will after a time start shutting down and thus passing hot primary water to the other circuit. When they've all shut down, the only flow left - necessary to keep the pump happy - is through the bypass system.

It may take noticeably longer to get a tankful of DHW under these circumstances, and you may need to anticipate family demands for DHW and room heating! Starting with last night's DHW still in the tank goes a fair way to getting everything up to temperature sooner - starting with a tankful of cold water straight from the mains means much longer for everything to heat up.

On the sytem I had, heating up a tank of mains-cold water took about an hour. Starting with last night's DHW in the tank, it took an hour to heat the water and get the rooms warm. Conserving hot water in this way can help a lot, as can anticipating family demands. After all the upheaval of the last few days, take time to ensure the lagging jacket on the HWT is properly fitted.

I'm glad I was able to help - but you do need to get the DHW temperature right for you by adjusting the TRV-like caplillary-valve settings.

Well, I've just taken over a house with a complex thermal-store system and more than twice the number of radiators I had - some of the radiators have TRVs and some don't, and there's a room thermostat as well. Although the system in seven years old, all the lockshield valves (LSVs) on the radiators are fully open, meaning the system has never been balanced. Using the groups' FAQ, I have now set about this task, you can find it here:

I would caution you not to make too many changes to your system at one time, otherwise you could easily get lost in maze of changes that don't give you the results you anticipated. You've come a long way to get the DHW system started, and you need to fine-tune that. With the DHW system running satisfactorily, there'll be the whole new world of Central Heating to explore....take it one step at a time. Good Luck!

TF

[Roger Mills]

After how long? The return from the coil won't be very hot until the water in the cylinder has heated up quite a lot - whereas the by-pass

*will* be hot if there's water flowing through it.

It shouldn't take 90 minutes to heat a tankful of water. It may take more than 30, but even then, the water at the top should be hot.

It should be better!

Yes, I'm sure he meant the boiler stat.

Yes. I suspect that water still isn't flowing through the coil as fast as it should. Try running with the thermostatic head removed, having made sure that the pin is fully up.

It is an extremely important safety measure - particularly when you have a plastic header tank in the attic (which you don't appear to have).

I think you should seriously consider upgrading the controls of your system by replacing the manual heating valve with a motorised zone valve, and replacing the TRV-like cylinder valve with a zone valve plus cylinder stat, with independent timers for each circuit - in other words, convert it to a proper S-Plan system.