Dingdongler

Hi guys.

My boiler broke down last Sunday. I've had npower and british gas out and neither could fix it, muppets!

I've had another plumber come out who thinks the heat exchanger has gone, but is now away for a week! So I've got no functioning boiler and so no hot water or heating for a week at least!

I have a big cylinder in the loft, and I've been told that the main water in this is for the central heating, and then tap/shower water travels through this to get hot.

Anyway, there is an immersion element in the cylinder which I never had connected up, when it was first fitted 4 years ago, and so has never been used. I had a sparky connect it up on xmas eve, and the thermostat is set to max, 60 degrees.

It's been making a noise, so its 'working', however I still don't really have any hot water (or heating)

Any idea what maybe wrong with it?

Thanks

Frosty The Snowman

Make sure your central heating pump is off, you don't want the cold water from that cycling through the tank.

See if that helps, if not turn the thermostat up a bit to 70C.

Immersion heater is not meant to heat the whole house. When my heating went I used fan heaters but if you can avoid those do as the air gets very dry, those oil filled rads do a decent job.

Dingdongler

Thanks mate. Could the central heating pumps still be working if I've got the heating switched off from the electronic honeywell controller?

I wasn't expecting the immersion to heat the house, but thought I would get hot water. I got about 1 minute of hotwater this morning, then it went cold. I don't understand that, and I've got the thermostat on max.

Thanks

Frosty The Snowman

Nah the pumb should be off if the controller is off. If you put your hand over the pump you will feel if it's going.

Maybe the immersion itself is borked, or not the right one, as mine gave me a tank full of piping hot water quite quickly when my heating let go.

Sorry I know that's no help!!

f1_fan

iTrader: (9)

Other way round I would think. The main water in the tank is for your hot water taps and is heated by a coil containing water pumped from the boiler. There will be a diverter valve to send the hot water through the tank only (hot water only) or through the tank and the rads (hot water plus central heating).

Your immersion heater is an electrical element that heats the water in the tank directly. If you are getting no hot water from the imersion heater I am guessing it may be goosed.

Dingdongler

I was told that my storage cylinder works the other way around to most, so the opposite to the way you suggested.

If there is power going to the electrical element, what could actually be wrong with it? If it gets caked in limescale/crud, would that make it virtually useless?. Can I pull the element straight out through its entry point, will I have to drain the cylinder first?

alcazar

iTrader: (2)

Do you have access to a multimeter, and a mains tester?

First check the fuse/circuit breaker that FEEDS the immersion.

Next, unscrew the plastic cap off the immersion, where the wire goes in, switch it on and carefully check that live IS live with the mains tester.

Switch off again, and test the heater with the multimeter to see if it has any resisitance: it should have SOME, not huge and certainly not infinite.
If you get this last, it's fekked.

Yes, you WILL have to drain the tank slightly to remove it. There SHOULD be a drain-off valve on the pipe leading to the base of the tank, near it's base, and that pipe should also have a valve on it further up it. Close the higher valve, attach pipe to drain-off and...well, drain off for a few minutes before unscrewing the immersion. You'll probably need a special tool: Wickes do them as do Screwfix, both are open for a new immersion today.

Best of luck.

Dingdongler

Hi Alcazar,

The sparky came around late on xmas eve and we didn't have much time. The cylinder is in the loft. As a temporary measure he connected it with wire and a normal 3 pin plug ie: wire is wired into immersion then coming down through the loft hatch and plugged in to a normal wall socket.

This shouldn't make any difference should it?

Thanks

JDM_Stig

iTrader: (3)

How long is the immersion on heating the water ?
I use 15 mins in the summer and that is still very hot in the afternoon if i have just had a wash in the morning(so not much cold water added)
As has been said if the central heating pump is running(shouldnt be if the heating is switched off by the fused spur) it will cool your water,
So maybe try 30 mins on the plug top.

f1_fan

iTrader: (9)

If that is the case then I think the immersion heater couldn't ever work as it is sitting in the water to be heated for the central heating system.

Rob Day

iTrader: (78)

Is there a bleed off somewhere to the outside? I know this is a different case but my boiler failed the other day too, its only three year old and is a condensing type. I tried alsorts then it occured to me that the condeser runs outside. SO i bolied the kettle and poured it on the pipe outside and lots of ice came out follwing lots of water, the boiler the cranked up fine and back to normal. All im saying is if you have a overflow pipe or something it may be frozen preventing the boiler cranking up properly, and if it does it may trip due to a danger the water cannot pass through the overflow. HTH

Dingdongler

F1 fan; I see where you are coming from. My cylinder has two pumps, one to send water to the boiler and one to send hot water to the rads.

If I've got the central heating switched off, ie so neither pump is running, do you still think I would never get hot water with the immersion? I thought the water in the cylinder would get hot, and then the cold water coil running through would be heated as it passed through this hot water, and then hey presto, hot water at the taps!

Uk300, yes, very good idea, it does happen. Thing is temps outside are now well below freezing, so even if there was ice in it, it should have melted.

f1_fan

iTrader: (9)

Well unless the tank contains a proper heat exchanger I doubt the water passing through the tank would be heated anything like enough by the hot water in the tank and this is where my confusion comes from about how your tank works in the first place.

I also see on another thread you mention having a combi boiler which begs the question why have you got a tank at all?

I am sorry if I am not being helpful as I am not a plumber, but I do understand most domestic heating systems and something does not add up here.

Generally combi systems have no tanks or if they do it is a small tank of hot water maintained in low water pressure areas so good amount of hot water is available instantly.

I have to say I have never heard of a tank working the way yours does and can't see what the point would be. I think you need to get a plumber to have a look at it and see what's what.

Sorry I can't be of any more help than that.

alcazar

iTrader: (2)

I'd be inclined to check both the fuse/circuit-breaker for that circuit, plus the one in the plug.

Check that power is GETTING to the immersion before all else, as decribed above.

I've looked at heaters and most seem to be 3kW, so a plug with a 13A fuse OUGHT to be OK, but check anyway.

Dingdongler

F1, the point of the thermal store is that hot water is 1) mains pressure 2) unlimited. We have three showers and a bath, another shower will be added in the future.

Like with all systems, there are pros and cons, but I was told this was a way to have mains pressure vigourous showers and an unlimited supply of hotwater.

Thanks for your input.

Alcazar, its making noise, so I'm fairly sure it's got power, and yes its 2.8kw.

Anyway, looks like I'm not going to have hot water or central heating until the New Year. Problem is the guy who fitted my system has emigrated and quite a few plumbers seem confused by my system. They don't want to commit to what the problem is.

After reading and listening, and seeing what the plumbers have checked and declared NOT to be the problem, I think the heat exchanger in the boiler has got blocked. The crud has probably come from cylinder, which according to the web is a known culprit for this. So I'll get the plumber to change the exchanger, clean the cylinder, and powerflush. I hope that fixes it!

f1_fan

iTrader: (9)

OK and that makes sense except that would mean the water in the tank was kept hot and usedfor the hot water taps and not for the central heating. That is not what you described earlier. The way you talked about it earlier I can't see how it would help with having 3 showers etc.

I am not trying to be awkward but once we undertsand what the water in the tank does then we can work out what the immersion heater is or is not doing.

Dingdongler

I don't feel you are being awkward at all, you're being helpful.

The water in the cylinder is for the central heating. Cold mains runs through this via a high efficiency coil. By the time it goes through its meant to be at the same temp as the ch water. This would be too hot to pass into the taps, so it goes via a blending valve where it is mixed with cold water again to reach a temp of 55 degs.

So, the unlimited supply of mains pressure hot water is achieved by cold mains running via a heat exchanging coil through the cylinder which is full of central heating water.

I hope that makes sense.

f1_fan

iTrader: (9)

Yes it does, but it sure seems an odd way of doing it. Anyway that's not really for me to say. There will no doubt be a reason for it.

In that case I would say that for the system to work with the immersion heater the water in the tank needs to be the same temp as it would if the boiler were working. Now you said you set it to 60 degrees and hence this should work, but is there a chance that the water passing through the high efficiency coil in the tank has already been heated by the boiler's combi system too. i.e. is it a two stage process?

Normally a combi can deliver a good supply of hot water, but rarely at mains pressure - I wonder if your system use a two stage process to ensure the hot water is plentiful.

If that were the case then the immersion heater would not be enough.

That is a real stab in the dark, but my best guess other than the immersion heater itself being duff.

If the immersion heater is on top of the tank you could unplug it and remove it and then test it by plugging it in once it is out of the tank and seeing if it starts to get warm at all. Obviiusly take sensible precautions, but miught be worth a try.

Rob Day

iTrader: (78)

I know this may sound a little criticising but you can get boliers that can power central heating and hot water (ie a combo boiler) that will power your needs (3 showers, baths etc). There not cheap but they sound a dam sight easier then going to the tank form which takes up room. Just being honest, wish you look, and if your near me in Lancs im sure i can offer a good plumber before newyear. Rob

Adrian F

Sounds like a typical high demand type hot water installation, by having the mass of water in the cyclinder hot all the time it allows for a much higher level of demand to be meet and sustained than by a combi boiler feeding all these units directly.

The small quantity of hot water that you have managed to get by using the imersion could be just the volume of the coil sitting in the thermal store and the rest runs through the store so fast it doesnt pick up enough heat as the immersion element isnt big enough to warm the mass of the thermal store to the required temperature?

Try reducing the flow rate and seeing if that then means the water coming out is warmer, i would suggest on this type of system one 2.4kw element will struggle i would expect to see at least 2 X 3kw elements depending on the cyclinder size and therfore mass of water to be heated it could require 3 phase elements to heat it properly.

Sounds like you need a plumber who is trained to work on that type of system, we use to work on the electric types called Pulsacoil.

Dingdongler

Thanks guys. The system does seem to confuse lots of people, including plumberd. The latter often suggest that the installer has has installed a crap system, but I've looked into it. It is one of the accepted approaches to a high demand sitiation as Adrian mentioned.

F1, the water in the coil is ONLY heated by the cylinder water not the boiler, as its a direct cold mains feed.

I wonder if Adrian F is right, and I don't have enough elements. The cylinder is huge, its about 6.5feet tall. Adrian what's a 'three phase' immersion.

Something else has confused me though. Reading through the user guide of the cylinder (Albion mainsflow) it says the water in the cylinder needs to be kept at a constant 70 (?75) degrees, and this is done by way of an immersion thermostat.

But my immersion thermostat, if its one and the same thing, was only connected 2 days ago, after 4 years of use! What's that all about???



Ps, thanks for your kind offer UKP, but I'm nowhere near Lancs.

Dingdongler

Thanks guys. The system does seem to confuse lots of people, including plumberd. The latter often suggest that the installer has has installed a crap system, but I've looked into it. It is one of the accepted approaches to a high demand sitiation as Adrian mentioned.

F1, the water in the coil is ONLY heated by the cylinder water not the boiler, as its a direct cold mains feed.

I wonder if Adrian F is right, and I don't have enough elements. The cylinder is huge, its about 6.5feet tall. Adrian what's a 'three phase' immersion.

Something else has confused me though. Reading through the user guide of the cylinder (Albion mainsflow) it says the water in the cylinder needs to be kept at a constant 70 (?75) degrees, and this is done by way of an immersion thermostat.

But my immersion thermostat, if its one and the same thing, was only connected 2 days ago, after 4 years of use! What's that all about???



Ps, thanks for your kind offer UKP, but I'm nowhere near Lancs.

mart360

For the sake of £40 ish, get down to screwfix and get a new immersion element. turn off the mains, and wire it in, set the element stat to 70c and leave it for 3 hrs, have no CH switched on (no pumps running) and then turn on a tap, if alls well, you should have HW


Mart

Dingdongler

Mart, the problem is I will have to drain out the tank first, correct? This is where it gets a bit complicated, for me anyway.

I'm not sure I know how to drain it, where to drain it to (it's in the loft), and how to make sure it doesn't fill itself whilst I'm draining it.

Sorry if that sounds like I'm a bit of a wuss, I'm just not that 'handy'

Thanks

f1_fan

iTrader: (9)

OK done a bit of reading and I reckon you have what is known as a thermal store system.

I think there are possibly one or both of two problems here.

1. The immersion heater is simply not powerful eneiough - water in your tank I reckon needs to be 70-75 degrees.

2. When you turn on a hot tap there should be a flow valve that detects this and pumps water from the the top of the store round the heat exchnager returning it to the bottom of the store and heating the mains water running through the heat exchanger which is then possibly blended with cold again to produce hot water at the tap of the right temperature.

Is there a chance this is all switched off for some reason so the water is just running through the heat exchnager with no water from the tank being circulated through the other side?

Dingdongler

F1, it is indeed a thermal store.

You maybe correct about the immersion element not being up to the job. I have also read that the water in the tank needs to be 70-75 degrees, the maximal setting on the immersion is 60 degrees. This, combined with the fact its a huge tank and perhaps some limescale could be rendering it useless.

On your point 2); I didn't think the main body of water was pumped from top to bottom in the manner you describe, I thought it remained static. But I could very well be wrong. There is definately a blending valve involved, that is meant to bring the tap water from a potential 70 degrees to 55 degrees.

Its been a cold, cold Christmas at the Dingdongler's this year!

f1_fan

iTrader: (9)

Well even if it isnt pumped then a flow valve will have to open to prevent hot water running through the heat exchnager all the time. Pretty sure it must be pumped as well though as hot water rises.

mart360

Found this

Heat Bank Thermal Stores - How They Work

shows a typical schematic/ operation

looks like an imersion coil is fitted midway into the unit..

this would require a drain down past the immersion level so it can be removed/ replaced, thats

assuming the immersion heater is shot, it may just be the tank stat or the immersion stat is kaput


how is the water currently heated? gas or electric



Mart

Dingdongler

Thanks Mart. I've almost given up on the immersion, I'm concentrating on what might be wrong with the whole system so I can plan a definitive course of action ie the boiler starts banging loudly at about 50 degrees and then shuts down. The boiler is meant to reach 75+ degrees.

Working diagnoses is the heat exhanger in the boiler is blocked/shot, likely due to sludge thrown out from the cylinder (they have a bit of a rep for that, according to the web!)

Here are some pics, they tally quite closely with the schematics you have linked to, except I have two pumps. I believe the one you can see to the left is to the boiler and the one to the right/in front is to the rads/heating.







You can't see the immersion/stat its obscured. The other white thermostat you can see towards the bottom (inserted into cylinder)is connected to the white 'box' marked 'honeywell'. The control panel I have downstairs is also marked 'honeywell'. so I presume that this white thermostat is what is meant to keep the water at 75 degrees?

Now, I just need to figure out if my working diagnoses is correct. Here are the clues

1) As mentioned, if I try and get the boiler past 50 degrees it starts to bang loudly (ie water is getting too hot because its not circulating) then shuts down. It modulates alot.

2) Visible inspection of the boiler (just with the cover off) reveals nil. Its had the return thermistor changed, no result.

3) The outflow of the boiler is patent

4) All rads have been bled, no air at all, and water seems clear.

5) Both pumps by the cylinder are working. They have been bled, and I was told no air, but water seemed a little dark/blackish.

6) I have noticed something. I have the boiler on really low, ie under 50 degrees, just so I cn have tepid water, rather than icy cold. The pump you see on the left of the cylinder, which I think is to the boiler, is working and feels quite hot. Not boiling, can't touch it hot, but hot. Not sure if that means anything.

Anyway, do we agree that the problem is probably a boiler thats blocked, probably as a consequence of muck from the cylinder?

My plan is to ask the plumber to replace the boiler(I'm fed up with it), service the cylinder and clear it of any sludge, and power flush the system. Could it be anything else?

Thanks

greatgonzo

iTrader: (1)

It sounds like the pump to the boiler! I know you said its running, but if you take out the centre screw as if you where venting it and gentle put a screw driver in the center you should feel it spinning, If you apply a little more pressure and you can slow it down then its probably shot.