Hot water in F/E tank. Hot water trickle out tap. Steam loft

[JohnHamer1977]

hi oilman -
yes the flow from the cold tap in the bath and in the bathroom sink is very good... I would go as far as to say the flow is very strong.

Maybe relevant information:
Just to cover all cold water flow I can think off, the toilet cistern seems to fill up pretty quickly as well

So the blockage is between the tap on the pipe going up the wall (stop cock?) and the small black insulated tank (hot tank?) that is in the loft?
Right?



RE: the thermastat
I have turned the electric off.
Took out the thermastat out... it didn't un-screw just pulled out.
BUT when un-wiring the brown mains wire the wires sheeth/plastic insulation was burnt to a crisp.
The white wire the other side was OK.

 

[oilman]

.........l

So the blockage is between the tap on the pipe going up the wall (stop cock?) and the small black insulated tank (hot tank?) that is in the loft?
Right?
..........................

NO. I had assumed the stopcock was in the pipe feeding the hot tank. It will be a blockage somewhere between the big tank in the loft and the hot tap.

Incidentally, the when you turn on the bathroom cold taps, does the loft tank start to refill?

 

[JohnHamer1977]

have got to go out now.
I will see if B&Q have another thermastat to replace this on but also have to do some other stuff so will not be back till later this evening I will reply to any messages then.

Thanks again

 

[JohnHamer1977]

what route does the water take from the BIG cold water tank in the loft and the hot tap?
does anyone have a diagram?

 

[oilman]

We all have diaphrams, breathing would be difficult otherwise.

 

[JohnHamer1977]

LOL yeh, but can you un-block them with a piece of wire.


Right, I have fitted the new 18" B&Q thermastat.
Only thing is, it's say not to turn the cylider back on untilrefolled with water.
Well I dipped the new stat in and out and it's bone dry so not full of water so I have not turned it back on.

So it looks to me as my Immersion is not filling up?
What next?

 

[oilman]

um.......noooooooo it's the tank that should be full of water, and it will be if you get water out of the hot tap.

 

[JohnHamer1977]

so the cylinder should NOT be full?

do you think it's OK to try then? even with the slow flow to the hot taps?
are we/me still thinking I have a block between the small tank and the cylinder...
I am still confused, is this what my system is?

or this

 

[oilman]

Water wont come out of the hot tap unless the cylinder is full. BUT I think you might have a problem inside the cylinder. You can try thr immersion heater with the thermostat set to say 50 deg, then watch for steam. If you get steam, there IS a problem with scale in the tank. You can investigate this by taking the immersion heater out and looking inside. You need to turn off the outlet from the cold tank to do this.

Have you put a new cable to the immersion heater? I take no responsibility if you haven"t. (I don't take responsibility anyway).

 

[Softus]

Right, I have fitted the new 18" B&Q thermastat.
Only thing is, it's say not to turn the cylider back on untilrefolled with water.
Well I dipped the new stat in and out and it's bone dry so not full of water so I have not turned it back on.

So it looks to me as my Immersion is not filling up?
What next?

John, the piece of knowledge you're missing here is that the pocket the thermostat sits inside is designed to be bone dry. So, if water is coming out of the hot taps, and you have wired up the thermostat correctly, then you are OK to switch on the immersion heater once again.

 

[JohnHamer1977]

Water wont come out of the hot tap unless the cylinder is full. BUT I think you might have a problem inside the cylinder. You can try thr immersion heater with the thermostat set to say 50 deg, then watch for steam. If you get steam, there IS a problem with scale in the tank. You can investigate this by taking the immersion heater out and looking inside. You need to turn off the outlet from the cold tank to do this.

Have you put a new cable to the immersion heater? I take no responsibility if you haven"t. (I don't take responsibility anyway).

OK, will set it lower to 50 deg tomorrow and investigate further (can not mess now as my son is in bed)

Is the "outlet" the tap on the wall in the photo I posted


New cable? No, but I did cut burnt bits back to good wire.
The only instructions in the the thermastat box were not brillient but I connected it how the other one came off.
I think the white link wire went to (E) and the brown live to (T) on the stat.
The others I only cut down to good wire and re-connected.


Maybe other relevant info:
I opened the old stat up (broke the plastic off the top) and the internal contacts were burned also - so that was deffinatly a factor... what would cause it to burn out like this?

 

[JohnHamer1977]

Brillient... so now really just have to check for steam.


Anyone -
if the Immersion does have a scale problem, is this why the I have slow flow... due to restricted current on the hot water out flow to taps?

Also, can anyone tell me if either of these are like my Immersion

thanks

 

[Softus]

Also, can anyone tell me if either of these are like my Immersion

John, now's about the time that it would be good to use the same terminology, so that there is no confusion.

You have an indirect DHW (domestic hot water) system, which means that the source of heat (the boiler) has no direct contact with the water that comes out of the taps. The sketch on the right illustrates this.

The purpose of the immersion heater is to be a backup, should the boiler (or one of the system controls) fail, or should you wish to turn the boiler off, during, say, the summer.

Thermostats, like everything in life, don't last forever. When they fail it will almost always be the result of overheating, as in your case, where the resistance across the contacts is much too high.

The excess water in the loft is not steam, but it is, to pedantic, water vapour. Subtle difference, but we may as well share the same plumbing vocabulary.

Turning to the flow problem, if it's poor from every hot tap in the house, then the blockage, which could be an air lock, is at a common point. The thing you refer to as the "immersion" is probably what I'd call the cylinder. The outlet from this (which is at the top) is capable of being blocked by scale, and scale is capable of being dislodged by an immersion heater element (the bit that actually does get wet) getting too hot for too long.

Scale can also, very easily, be dislodged from within the cold cistern, in the loft, and enter the outlet from the cistern - the one that feeds the cylinder.

I suggest, unless someone else offers a better idea, that you cut the copper pipe that emerges from the cylinder, at a point that can later be re-connected using a compression coupling (or a pushfit one), and poke a something flexible, like a curtain wire, into the top of the cylinder. To be specific, this is the pipe that emerges from the very top of the cylinder, not any of the ones at the side.

You can do this with a full cylinder, but you'll need to isolate the cold supply to the cylinder. If there is a functioning valve, then use it, otherwise you'll have to shut off the cold supply to the cistern, and let it empty using, say, the bath cold tap and/or hot tap.

Does this make sense so far? If not then please ask before I douse you with more information.

 

[JohnHamer1977]

Hi... no the info is very clear thanks for that.
Thanks for ID'ing my type of cylinder.

Some more Q's for you if it's not too much bother
1. whats the differance between steam and water vapour? (just out of curiosity)

2. when you say the purpose of the Immersion heater is as back-up... does that mean I shouldn't need to have mine on at all if I left my kitchen boiler on "constant" on the timer?

3. Air-lock, I have tried 2 methods of sorting the air lock... one via hand over a mixer tap and the other using my washing machine pipes and hose.
Can I pressume we have pretty much eliminated that as a cause?
So I am now buying into the scale problem and acting accordingly, right?

4. I have previously mention when we 1st moved in the hot water stoped coming out of taps altogether... a plumber tod us it was a "diaphram" he un blocked with a bit of wire somewhere in the loft.
Did I get blagged? or is there a diaphram that a piece of wire can un-block.
If yes, I know this can make the hot taps flow or not flow but could it also cause a slow flow like in my case?

5. (please see pic)
there seems to be 2 stopcocks... one is in the picture and one is on a pipe that goes between the big cold water tank and the smaller insulated tank in the loft... which one do I need to turn off before proceeding with cutting the pipe as you described.

also, I have identified 2 potential cutting points A and B which if any of these are best to use... if niether can you describe a better place?

I am going to be poking into the cylinder but what if it's above that point shall I poke upward whie I am there, after that how do I check further up EG. right at the cold cistern in the loft?

Cheers

 

[ChrisR]

Deary me, what a lot of....

John look carefully at the diag you posted from discountedheating and you'll see a VENT pipe going up from the HW cylinder, OK? That fills with hot water, so if there's any blockage in the cylinder or its supply, you get a quick burst of hw which comes down the vent pipe.

You haven't mentioned that so lets assume what the logic says...

---

It could be that your CW is all on the mains??(unless I've missed something) In which case your HW flow will seem poor, so MEASURE it, litres per minute; bucket = about 9 litres. Bucket in a minute is about normal

Could it be you have iron hw feed pipes? - they get a bit rusty and restricted. Any sign of coloured water?

I would expect that that galv cistern in the loft is getting rusty and bits are sticking in the pipes. That's about all anyone could poke out with a bit of wire - until they stick in a valve somewhere. Can be impossible to shift without dismantling pipes from valves.


By the way your heating controller would normally have something on it about hot water, or a timer which brings the boiler on separately(for heating hw) from the pump(which shoves the boiler water round the rads).