Thermal Store problems

[Flange]

Hi guys (and gals)
I hope you can help me. Will try to keep it fairly brief!
Have a Torrent ECO with woodburner downstairs, so gravity. All working well for the past year, apart from rads getting hot then cool (as the water gets pushed round the system) so instead of standing with my hand on the rad flow pipe to turn the heating off in order for the store to heat up again, I wanted a pipe stat to turn the pump on at temp (55 deg?). Also, I wanted the CH timeswitch moved downstairs.
Leccy man (a qualified friend in the area) duly moved Drayton Lifestyle downstairs (and immersion controls but that is separate and all fine), and wired in pipe stat. All seemed ok but tank not hot so not tested.
Later I had a bath using immersion and didn't want to waste a tankful of hot water so turned the heating from off to timed, and the fuse tripped.
Disconnected pipe stat and is not tripping anymore BUT the CH pump is now continually running (both valves are also vibrating) although the CH timeswitch is set to OFF.
I replaced the boiler overheat stat and still pump is ON.
So....
1. Can anyone see a glaring fault in my diagram (without pipe stat)?
2. Is this how it is supposed to be wired? (with pipe stat)?

Many thanks in advance.

 

[buzzlightyear]

Can anyone see a glaring fault in my diagram

nice drawing by the way ,and there is a but, get a some body in that can help you.

 

[Flange]

Ta! And thought someone might say that . I've had a bit of trouble finding someone to help, and grabbed my friend when he came down. Thermal stores seem to be avoided like the plague by electricians for some reason!

 

[Flange]

To clarify: my electrician friend is stumped (and a bit embarrassed). I have taken photos etc to send to him, as he doesn't live near me. I posted the drawn pics because I thought the photo would be unclear (and I'm a bit OCD about visual aids, lol). This is (or was!) an up and running system for my place in the sticks. And as I am lime plastering at the mo, it's a right pain not being able to have a bath! Even a clue would help at this stage! I'm practically pleading

 

[Flange]

The pipe stat drawing is mine, though. I think it was wired wrong before, as he followed the Torrent wiring plan but that pipe stat was meant to be placed on the return flow from the stove, if I'm not mistaken. I know it has to be wired in series from the programmer, and I think it's C + 2 to open at temp? It's still a secondary issue, though.

 

[Wilko]

Hi - exactly what is it that trips?

 

[Flange]

I think it was the front ring (my house is wired in quarters) when I switched the programmer from off to timed. The control panel is wired to a fused spur.

 

[Flange]

If this helps....

 

[buzzlightyear]

flange ,take all the tails out and start again ,start with wiring plan and start putting the tails one by one ,it could be no simpler .

 

[Wilko]

Hi - ok, was it an RCD trip, an MCB trip or a fuse blow? Then which circuit is it on? Then does it happen twice (say).

 

[PEG]

Hi,a bit more of a description of the layout,would help. How is the gravity/pumped sections arranged? What other electrical items are on the same power circuit(s)?

It is perfectly possible,if it worked previously,that an individual component,has an issue. This would need tracing,using standard tactics.

Even when viewing cables,in a wiring junction box,is no use,if we don't know how and why they connect,at the other end
Just banking that they do...is fatal,in the fault finding job.

 

[marconi]

I am with PEG - need much better description and diagram of the plumbing system and how you want it to work and be controlled. Some pictures always help add clarity to explanations.

 

[Flange]

Hi,a bit more of a description of the layout,would help. How is the gravity/pumped sections arranged? What other electrical items are on the same power circuit(s)?

It is perfectly possible,if it worked previously,that an individual component,has an issue. This would need tracing,using standard tactics.

Even when viewing cables,in a wiring junction box,is no use,if we don't know how and why they connect,at the other end
Just banking that they do...is fatal,in the fault finding job.

Gravity water from woodburner downstairs to thermal store upstairs. Pump on rads coming from store.
Fused spur supplying feed to control panel only upstairs.
Has my first post, with the diagrams, disappeared?

 

[Flange]

I am with PEG - need much better description and diagram of the plumbing system and how you want it to work and be controlled. Some pictures always help add clarity to explanations.

Have my wiring plan posts disappeared? I can still see them...

 

[marconi]

I am with PEG - need much better description and diagram of the plumbing system and how you want it to work and be controlled. Some pictures always help add clarity to explanations.

No, your wiring plans have not disappeared....

 

[Flange]

Oh, I see! Sorry. Here is a plan of my system (thank god for Paint, haha). Obviously it has immersions but they are separate and working fine. My system is very basic.

 

[Flange]

Update: I have found someone to have a look but they can't come out until next Friday. If I could have a bath before then, I'd be very happy!

 

[buzzlightyear]

Update: I have found someone to have a look but they can't come out until next Friday. If I could have a bath before then, I'd be very happy

you can still get the old tin baths you know .

Galvanised Tin Bath - 35 in x 21 in x 12 in - too big to post | eBay - https://www.ebay.co.uk/itm/Galvanised-Tin-Bath-35-in-x-21-in-x-12-in-too-big-to-post-/312348250410

 

[Flange]

you can still get the old tin baths you know .

Galvanised Tin Bath - 35 in x 21 in x 12 in - too big to post | eBay - https://www.ebay.co.uk/itm/Galvanised-Tin-Bath-35-in-x-21-in-x-12-in-too-big-to-post-/312348250410

Haha, I'll stick it on the bonfire...

 

[PEG]

Hi bud,it was a diagram of your particular layout,i was after,not Gledhill's generic drawing. The operation,and therefore the possible issues,are specific to each system,on an individual basis.

The addition or omission of a loader,or gravity flap,pump,feed or vent,in the wrong place,may or may not cause an immediate problem,until the day another thing changes,then....

If your system worked fine until presently,and has only now started tripping out,it very well could be a fail of a single,electrical item. It could be that a situation has occurred in the system,where two components switch to a position they have not normally found themselves,and this has caused the problem.

If you have someone coming out,then hopefully you can get sorted and clean ....but if your system looks identical to that generic picture...i'll dress as Gladis Emmanuel and bed-bath you myself

 

[marconi]

First, I agree with PEG (#20) about employing an electrician to inspect and test in order to diagnose the electrical fault.

I am interested in helping you with this plumbing aspect of your problem:
' All working well for the past year, apart from rads getting hot then cool (as the water gets pushed round the system) so instead of standing with my hand on the rad flow pipe to turn the heating off in order for the store to heat up again, I wanted a pipe stat to turn the pump on at temp (55 deg?)'

I wanted to see an 'as installed plumbing diagram' to see where you had located the pipe stat - I assume you have put it into the radiator flow out pipe from the thermostore. I think this will be problematic because you will indeed have flow when the flow is above the preset temperature but when the temperature drops and the stat turns off, so does the flow; consequentially the water in the pipe will cool down - because there is no flow - and there can never be any further flow because the pump is not running because the stat is off because the water is too cold.

I think the pipe stat should be placed in the out flow pipe between the back boiler and the heatsink radiator after the normally open valve which feeds it. This way the pipe stat will detect when the water in the thermostore is at a high enough temperature to allow flow to begin through the other radiators. You would use the Normally Open contacts of the pipe stat in series with the pump line supply. By some trial and error you can set a suitable switching temperature. More simply this arrangements makes the household radiators warm up in tandem with the heat sink radiator and stops flow when the hot water from the back boiler is diverted to heat up the thermostore. It also stops the pump running when the back boiler is not lit.

 

[Flange]

Thank you, Marconi, for your detailed reply. Very much appreciated. Wouldn't I still have the same problem though, regarding the cold CH water being pumped around and then waiting for the store to heat up again? With the pipe stat on the outflow from the store, I could set the temp at a min of 50-55 deg otherwise I am waiting for the cylinder stat to open the heatsink at around 85 deg?

 

[Flange]

If you have someone coming out,then hopefully you can get sorted and clean ....but if your system looks identical to that generic picture...i'll dress as Gladis Emmanuel and bed-bath you myself

At this moment in time... I'll take it!

 

[marconi]

Assumptions:

1. Solid fuel back boiler lit.
2. Timed on period for CH.
3. Room stat below fixed temp and hence on.

Now, with the thermostore at or above its tank stat temperature, the tank stat normally closed contacts are open which removes power from the heat sink radiator's normally open motorised valve -this valve opens allowing hot water under gravity to flow.The normally open contacts of this valve are open which removes power from the normally closed motorised tank valve between the back boiler and thermostore - hot water from the back boiler no longer flows through the thermostore heat exchanger. A pipe stat on the flow to the heat sink radiator will detect hot water and when above preset temp close the normally ope contacts supplying power to the pump. The pump circulates water through the other radiators, this water being heated by an exchanger in the thermostore - the thermostore water cools while heat is taken from it. When the thermostore tank stat drops below preset, its normally closed contact close which energises the heat sink radiator valve to close which in turn energises the normally closed rank valve to open. The back boiler now heats the thermostore again and flow through the heatsink radiator ceases; the water in the pipe cools and is sensed by the pipe state which eventually drops below preset enough to turn off the pump. There is thus a cycling between two states which depends on the rate at which heat is supplied to the thermostore by the back boiler circuit, the rate at which its is removed by the CH circuit, the upper temperature when the tank stat normally closed contacts open and the lower temperature when the same contacts close (hysteresis effect eg if you set 70C they might open at 75C and close at 60C which is important to prevent a rapid cycling rate which would be the case for say 71C and 69C).

What I think is a problem/feature you will have to contend with/accept is that the back boiler is relatively low powered compared to a gas boiler and relies on gravity flow. These factors mean it will take 'longer' to heat the thermostore by a back boiler than a powerful gas boiler. Ultimately energy is conserved and over time you cannot get out more heat energy than you put in. As controlled the system prioritises keeping the thermostore at its set point temperature, so if you drain the tank say for several large baths of hot water the CH and heat sink radiator will be off for a while as the back boiler heats the thermostore up.

Long winded - sorry. You get the gist. Others might have better ideas to contribute.

PS: My plumbers friends don't understand why the CH is fed by a heat exchanger in the thermostore rather than directly from the back boiler via a tank/CH diverter valve. But that is what the manufacturer's thermostore diagram shows, I guess to enable several sources of heat energy to be stored in one tank through a number of heat exchangers eg: gas boiler, solid fuel back boiler, solar panels, heat pump...

 

[PEG]

Just a little point,here,if a heat-sink radiator,is genuinely that,it will definitely not have a motorised valve,negating it's operation.