Boiler Not Heating Water

jc1980

Hi All,

Bit of a problem, turn the heating on to heat the water for a shower. Pump in the hot press automatically kicks in when I turn the boiler on (not sure why), radiators heat up normally. Problem is that the actual hot water tank isn't heating up so the shower and hot taps are pouring out cold water. Had been working grand until around Wednesday. Based in the Court if that makes an difference.

Avns1s

Was any of the manual valves closed? If you have a motorised valved for the hot water plumbing circuit, make sure it is opening. There is a manual override on them.

jc1980

Interesting, would theses automatically close if it got to cold? Where would the manual over ride be? On the boiler or in the hot press?

Avns1s

Make sure all valves are opened.

Cold shouldn' affect them unless something froze and that's highly unlikely given your heating is working normally.

The Motorised control valve can be either in your hotpress or close to your boiler. The override normally is like a slider on the side of the valve. You can't miss it.

Also, is there a thermostat anywhere on the cylinder that may have gotten turned down? This could be controlling the motorised valve.

pixbyjohn

Motorised valve looks like this or very similar

Motorised-Valve-HVAC-Valve-SEV3000- by pixbyjohn, on Flickr

jc1980

I've found the motorised value, and turn the little lever from flushing to normal use, as far as Im aware its always been on flushing. Just checked the shower, its still ice cold.

All the values are open from what I can see.

I've attached a picture of the set-up in the hotpress

Charlie-Bravo

Sounds like you might have an air-lock somewhere. Did you perhaps turn on or off any radiators before Wednesday? trapped air could have made its way to a point and just needs to get to the AAV (automatic air valve) as shown in top of your photo.

Check the pressure gauge on the Boiler. Ideally should be between 1 and 2 bar. Try bleeding all radiators, and then top up the system by opening for a very short period the black valve connected to the flexible pipe(as in your picture). When the heating kicks in it might push the air lock along.

Also, the AAV needs to be working - not sure how to check this, but maybe someone else might have experience with AAV's.

jc1980

I'll bleed the radiators now as I turned on the kitchen one recently. I've been topping it up alright, think its around 2.5 bar. Its strange because the heating is working fine, but just the hot water tank isn't heating up at all. Also the pump is constantly kicking in, pretty noisy.

pixbyjohn

It looks very likely that the hot feed into the worm of the hot water cylinder is blocked. Is that thermostatic valve in your photo feeding into or out of the cylinder worm ? Maybe that is faulty and restricting the flow through the worm. It doesn't appear to be an airlock because you have water coming from the hot tap albeit cold water.

Indirect%20cylinder by pixbyjohn, on Flickr

The flow and return to the worm is marked 3 and 4 and these pipes should be hot to allow the worm to heat the water in the cylinder. I hope this helps you.
Have you tried heating the cylinder with the immersion and does that work ?

Charlie-Bravo

pixbyjohn wrote: »

It doesn't appear to be an airlock because you have water coming from the hot tap albeit cold water.

I'm not saying the air lock is in the hot water supply pipework but in the separate central hreating system pipework preventing the flow through the calorifer.

pixbyjohn

jc1980 wrote: »

I'll bleed the radiators now as I turned on the kitchen one recently. I've been topping it up alright, think its around 2.5 bar. Its strange because the heating is working fine, but just the hot water tank isn't heating up at all. Also the pump is constantly kicking in, pretty noisy.

If you cure the problem , please post the results and how it was fixed,
Thanks

jc1980

Really appreciate all the help guys, I've a strong feeling that its a really simple problem. Unfortunitly no fix yet, I've the immersion on now so hopefully that will produce some hot water at least.

jc1980

Just an update guys, turned the immersion on and nothing happened. The hot water tank isnt heating at all and the pump is nearly always on. Getting pretty frustrated at this stage now, think I'll have to get a plumber to come and take a look for me.

pixbyjohn

Really a mystery, sorry I can't help.

jc1980

Good news lads, just had a friend of a friend take a look.

Problem was the white thermostat, it wasn't allowing the flow of water around the worm in the hot tank. He thinks it was faulty, and hence the reason why the pump was forever making noise. The pump would kick in and try push water around but the water was never going anywhere.

Now the fix was simple enough, remove the white thermostat on top. Ideally you should replace it, but thats going to cost €€€ and your going to need to bleed the system. He told me the thermostat is now set to the the highest setting, so there shouldnt be a need to change it down.

Avns1s

Well there's innovation, using a TRV to control the hot water in your cylinder. Innovative maybe but unlikely to be very effective as it is using the temperature of the hotpress to determine whether or not to allow the cylinder to be heated.

Anyway, at least you know what it is and glad you got sorted.

By the way, that TRV faulty or otherwise, should not have had any impact on your immersion working so it lookd like you might have one more (small) problem to sort.

jc1980

Not the ideal fix alright but still so long as it works, I'm happy enough. Might have also been a tiny bit of air in the system but he got that out by opening loosing the nuts and closing them when the hissing stopped.

Not entirely sure about the immersion, once the water heats off the heating it shouldnt need to be turned on. I'll keep a close eye on the whole things and let you know if any more issues come up.



Thanks for all the help once again Avns1s, pixbyjohn and astrofluff

Charlie-Bravo

You will not believe me when I say this...but I did look at the thermostat in the original pic and see it set to 5 so thought no more of it! Goes to show you...never rule out anything connected to the system.

Thanks for letting us know what the problem was - lesson learned.

pixbyjohn

pixbyjohn wrote: »

It looks very likely that the hot feed into the worm of the hot water cylinder is blocked. Is that thermostatic valve in your photo feeding into or out of the cylinder worm ? Maybe that is faulty and restricting the flow through the worm. ?

Thought it could have been that
Glad its working, thanks for letting us know the cure

d31b0y

I have the same system as jc1980 and I was just wondering, what is the difference between "normal use" and "flushing" on that automatic valve?

Mine was turned to normal use ever since I moved in, but I have been having trouble with the heating so I turned it to flushing last night and this morning the radiator in the bathroom is hotter than it has ever been.

pixbyjohn

A motorised valve is usually used in a heating circuit for the following reason. During the winter months your boiler will need to heat the radiator circuit as well as the domestic hot water in your copper cylinder. During the summer months you will not require heat at the radiators so you switch the motorised valve to the off position so as only the domestic hot water will heat.
The motorised valve is a simple stopcock really and will turn off the radiator circuit. Normal operation is normally used but in the case of a need to over ride the electrical actuator you can open the valve manually which is probably the flush position in your case.
Motorised valves can be 2 way or in a more elaborate system may be a 3 way to divert the flow to a different area of the house.

d'Oracle

Avns1s wrote: »

Well there's innovation, using a TRV to control the hot water in your cylinder. Innovative maybe but unlikely to be very effective as it is using the temperature of the hotpress to determine whether or not to allow the cylinder to be heated.

Anyway, at least you know what it is and glad you got sorted.

By the way, that TRV faulty or otherwise, should not have had any impact on your immersion working so it lookd like you might have one more (small) problem to sort.

Looks like one of those situations where the plumber doesn't understand what A cylinder thermostat is/is for.