My hot water tank has wiring for an immersion heater, but one isn't fitted. The tank, I would guess is about 20 years old.
Is the fitting standard - ie can I just buy an immersion heater and be sure it will fit?
Thanks
I don't understand what you've written: - "wiring for ... " but "is not fitted ... ". A hot water cylinder - 20 years old may be 'naked' copper with an external insulation blanket or foamed insulation clad - should have a large boss on the top for accepting an immersion heater. The immersion heater assembly should fit directly into, and replace, the boss. From what you've said - you should see a big nut hexagon on the top of your cylinder. Immersion heaters usually, when fitted have a cylindrical 'can' -all those I've encountered have been black - normally secured by a knurled nut off-centre within the 'can'. 'Wiring' normally makes contacts with terminals under the can. It's fitted on an installation -specific basis to the feed/source of the 'immersion heater' supply.
Where does your 'wiring for ..' start and finish? what is on the hot-water cylinder top?
Yes I see a big hexagon nut near the top at about 11:30 o'clock which fits this description of a boss.
Sorry, I could have been clearer. There is a mains wire going into the airing cupboard, but it terminates in a thermostat attached to the outside of the tank. There is no output cable from the thermostat. Presumably this is meant to continue on to an immersion heater?
The nut on the boss is slightly bigger than my biggest spanner, so I've not tried to remove it, also I don't want to introduce a chance of a leak until I've got a fair idea I can just put an immersion heater in there.
Steve
Presumably there is a fused spur next to the tank but no immersion heater fitted, ie a blanking plug.
sponix
More likely than not that is a cylinder stat that controls the boiler.
Immersion heaters normall have a built in thermostat-all they need is mains power.
sponix
Yes they are as long as there is a removable plug. You will need an immersion heater spanner.
Tip: It is safer to undo the plug using the spanner and tapping it, than to pull the spanner continuously. The copper is less likely to distort.
The heater should come with a fibre sealing washer, but some sealant such as Boss White or equivalent is needed for the threads.
I'm answering this _and only this _ point. What you see is the blanking plug for the immersion heater. That hexagon plug/boss is stopping water (hot) from pouring out of the top of the cylinder.
It ain't neccessarily so: - immersion heater _assemblies_ screw into the aperture we've decribed above, making a water tight seal. The assembly contains one or two elements each froming a 'U' shape [there can be a top-up heater and a longer full-cyclinder heater] on top of the assembly can usually be found a knob with an arrow pointing to a demand temperature for the heated water- this is sensed by a thermo-couple which itself is a long thin sensor fitting into a tube penetrating through the heating elements. In other words, the heating-sensing thermostat is contained within the 'Immersion Heater' assemby.
An external clamped thermostat is _usually_ indicative of a boiler supplied heating system - in this case the thermostat is telling the boiler to cease producing heat for the water. You _may_ be looking at a 'wire' coming from and returning to the boiler. It may not be the 'mains wire' that you think; although it _may_ be switching 'mains' in a similar fashion to a light switch. Be very careful when examing this cable, dependant on the boiler control circuitry it may be at mains voltage ... and probably changes dependant on whether your boiler is 'ON' 'OFF' CH HW or CH+HW .... :)
'Immersion spanners' are quite cheap and have only one use .... :) they can usually be found in the sheds adjacent to the cylinders in the plumbing sections. They are big hex cut-outs from cheapish metal usually with a shortish cranked handle. They're not pretty; but necessary.
What you _will need is an electrical feed for the immersion heater, Locating, and routing for such a service is IMHO beyond the scope of this post.
Yes I think the little thermostat 'is' something to do with the central heating, nothing to do with the immersion heater, I will leave well alone.
There is a separate power supply in the airing cupboard with it's own fusebox switch (next to the electricity consumer unit) marked 'shower' (though no shower was ever fitted). This is a pretty hefty cable.
I think I could use this for an immersion heater. I will get someonje in to look at it I think.
Thanks for all help.
How is your water currently heated, and why do you want an immersion heater?
Mine is heated by my gas central heating boiler - even in summer when the heating is off - and the immersion heater is used only in emergencies. If I didn't happen to have one, I don't think I'd suddenly be fitting one.
If the blanking plug has been in the cylinder for 20 years, it's going to be a s*d to remove - and you may well end up scrapping the cylinder in the process. [It's probably time for a new - fast recovery - model anyway!]
Because my boiler has just died and I have no hot water, I see an immersion heater as a good temporary measure to get hot water for a few weeks while the CH system is replaced. I'll probably be getting a combi boiler, so the tank will be thrown away anyway.
Fair enough - your emergency has already happened!
.....and the disaster of a combi boiler is to follow along shortly :-)
Ah - that'll need a new thread - but I agree!
NOT on the threads Andy - it sets like concrete! With an immersion heater the seal is between the flat face of the immersion and the face of the cylinder boss where the fibre joint is located. A light smear of compound on these faces to assist the fibre joint is all that should be required. I put a couple of turns of PTFE on the threads not as a seal but as a lubricant so the immersion can be removed later if required, without destroying the cylinder
I did mine a few weeks ago with no compound at all - with a few turns of PTFE for the same reason you used it.
I think there are plenty enough threads on that topic - it being covered here on a weekly basis!
More amateur tripe. Appalling.
You put NO compound on the thread. The immersion is supposed to have none whatsoever. Just clean the surfaces and tighten the immersion. The fibre washer may initially weep. But as it absorbs water it will expand making the seal. Try this first. If still a leak after the system has heated up, take it off and then lightly smear compound on both edges of the washer. Putting compound on the thread with act like glue and weld it in, in time, making some of them near impossible to remove.
Halleluiah! I've seen the light! Drivel said something sensible!
What is your bidding, Oh great one?
I doubt that. You appear beyond redemption.
Great way to do things. If it doesn't work, try again. Like hack sawing through plastic pipe.
Remind us once again how you earn a living? But obviously with no repeat customers?
Love the 'compound' bit. Anyone with more than one brain cell would name the product on a DIY group.
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