Boiler not heating hot water tank?

kittennose

Moved into a new property and just realised we have been using emersion heater 24/7 for the last few months (the switch was hidden behind shelving). Having thought the boiler was heating this up per our programme schedule, turning the emersion off made me realise the gas is NOT heating the hot water tank up!

Is there anything likely to be the culprit? Wonder if I am better off joining a Homeserve type care package and claiming on that (these are about £240 a year) or just paying for alocal plumber to repair.

Alex1983

Does the heating work?

Ebe_Scrooge

The first thing I'd check is that the programmer is set to heat the water. There are loads of different sorts of programmer, but most will have something to the effect of "Central Heating : Off/Timed/Constant, Water : Off/Timed/Constant".


Assuming the programmer is trying to heat the water, then a common problem is a stuck or faulty diverter valve ( this basically diverts the heat from the boiler to either the central heating or the hot water, as dictated by the programmer ). It's not uncommon for them to get stuck. Even if it's broken, it's not a particularly difficult or expensive job - any plumber/heating engineer will be able to take a look for you. If you fancy having a look yourself ( even if you don't feel confident in changing it ), you'll find any number of tutorials online showing how to check if it's stuck, and how to have a go at freeing it.


Personally I'm not a huge fan of these service packages like Homeserve etc. But like any form of insurance it's down to personal choice. But I would advise that you check very carefully what is - and more importantly, what is not - covered.

Wookey

Look for an air release valve in the hotpress, check you have adequate water in the system, make sure any stats are turned up enough to allow a flow of water thru any valves, check the operation of any electrically controlled valves and that there is power to them.

Le_Kirk

If you have now turned off the immersion heater, has there been time for the water in the cylinder to cool down sufficiently for the boiler to need to kick in? The immersion heater will have (probably) its own internal thermostat but the boiler will have one strapped to the hot water cylinder - check this is turned up to at least 65 deg C. Otherwise carry out checks as advised in other posts.

kittennose

Alex1983 wrote: »

Does the heating work?

Hello, yes the heating works OK.

kittennose

Wookey wrote: »

Look for an air release valve in the hotpress, check you have adequate water in the system, make sure any stats are turned up enough to allow a flow of water thru any valves, check the operation of any electrically controlled valves and that there is power to them.

Yes we have a hive thermostat, so dead simple to put water on / heating on separately. Rads work ok so it's heating water fine, just not pushing it to hot water tank.

If we put the water on without CH - the boiler is working and everything sounds like it's working. Just no hot water

We have a gravity fed system.

Alex1983

If your heating works, your boiler/ pump are both fine. Do you know what a 3 way valve is? Do you have 1 or do you have 2 zone vavles?

When you put hot water on without heating do your radiators heat up?

stator

Find the 3 port valve.
Turn on the HW but off the heating.
(carefully) Feel the pipe going from the 3 port valve into the HW tank. Is it warm or really hot?

Identify the type of 3 port valve motor you have. Remove the 3 port valve motor (most of them pop off by pushing a switch) and turn the 3 port valve with a large screwdriver. (It only moves a little bit, not a huge amount).
If you can manually turn the 3 port valve into the HW position and HW then flows to the HW tank, then you know the fault is either with the 3 port vale motor, or with the control system wiring to the 3 port valve.

If you can find the exactly model you can fit a like for like replacement 3 port valve motor yourself, just take careful notes and photos of the wiring before you remove the old one

Alex1983

Just realised you said it's gravity, do you mean old fashioned gravity hot water and pumped heating. If so you will have no valves and if the heating is working can only be airlock or blockage.

Johnhowell

Kittennose,

As per message No.5 above - Did you check the cylinder's thermostat? These can be turned down quite easily by the unwary. If the tank has an insulation blanket over it, as this can moved by the adding/taking out of bedding and blankets onto the storage shelves in the airing cupboard.

Could be the thermostat or port valve had failed and the previous owner switched over to immersion heater instead of getting it fixed.

I once noticed the hot water was getting hotter than usual and the dial had been nudged around.

Good luck