Hot water tank - Intermittent hissing

PancakeP

I have a hissing noise coming from my hot water tank. If I turn the power off to it, it stops (the water tank is in my bedroom) and it's hissing whether the hot water is turned on at the Programmer or not.
It's not constant, more like it's trying to cool itself down / release some pressure, then when it's done that, which takes it about 5 seconds it has a quiet time and then does it again approx 20/30 seconds later.
Any suggestions as to likely cause please?
Heating and hot water have both been lay fairly dormant for the last 4 months or so as house has been empty.

Also, not sure if it's relevant, the hot water coming out of the taps - I don't know if this is usual for this system or not as the house is new to me. Hot water tank is set at 60.

Thanks

macman

What sort of CH/DHW system do you have. Is this an immersion heater?

PancakeP

Hi
Yes it's the emersion heater that's doing the hissing.
Water tank in the loft, emersion heater in bedroom cupboard on first floor, combi boiler in the kitchen, on the ground floor.

keystone

If you have a hot water cylinder and a cold tank in roof you have an unvented system either with a conventional boiler or a modern condensing system boiler. You won't have a combi boiler. What does the label on the cylinder say? What is the boiler make/model?

Is it the immersion heater itself hissing or the cylinder - where is the hissing coming from - just roughly?

Any chance of a pic of the cylinder and pipework around it?

Cheers

Edit: Are there any autoairvents on the pipework?

PancakeP

Thanks.

The hissing is coming from the top of the emersion heater, the "top of the bottle" type area - it is a big water tank, with what looks like a "lid" on it, with a pipe/wire going in to it and it's that part the hissing is coming from.

I can get a pic, but won't be til tomorrow as I'm working away at the mo.

Boiler is a Potterton Profile. Programming unit sat next to the boiler is a Danfoss 5. I'm pretty sure the emersion heater is also a Danfoss.

keystone

Sounds like the immersion (you ain't taking the hint ) heater needs attention. Perhaps the fibre washer is knackered. Unless you have the correct tools and knowledge you'd better get someone in.

Oh and your boiler is an older balanced flue type. Certainly NOT a combi.

Cheers

PancakeP

Sorry re spelling, I'm new to this, although I'm thinking you'd already worked that out!
I will get someone in to come have a look at it. It would do the whole system good to have a bit of a service before the winter anyway.
Thanks for your help.
ps Immersion - got it now!!

muckybutt

It is quite common for immersion heaters to make a hissing noise when they are on, basically think of a kettle boiling - this is in effect what you have, it will be the noise of the water boiling on the element.
Mine does it ! .... always has done

keystone

as long as it isn't actually hissing implying a release of pressure rather than gently bubbling. I think OP might need to be a bit more specific as to the nature of the noise.

Cheers

southcoastrgi

immersion = the heating element
cylinder = the container that stores your hot water

closed

look for a small leak at the top of the cylinder, where the pipe comes out of the top, or where the immersion element is

if the water is heated up by a gas boiler, the immersion, (which is an electric element like a kettle) shouldn't be switched on at all, but the programmer should be.