No hot water when weather is cold

[gaz1250]

We have noticed over the last few weeks since the weather is close to freezing at night that we don’t get hot water, when the weather temp raised last weekend it went back to normal but the last few days it’s stoped again? Never had a problem in the past. Is something on its way to failing? Or something else? It’s a old gravity system but boiler only two year old, NOT a combi water, tank in the loft area

 

[Mottie]

Is that when you are running a shower? Perhaps turn the hot water temperature up a bit? When it’s cold, it’s mixing with colder water coming in so the water coming out of the taps will feel cooler.

 

[Murdochcat]

Can you heat water separately to heating ?

If you can heat your water mainly during the night when the heating is off

 

[gaz1250]

Yeah it can be switched on on its own, so you would recommend it being on in the night rather than say first thing in a morning?

 

[fixitflav]

We have noticed over the last few weeks since the weather is close to freezing at night that we don’t get hot water, when the weather temp raised last weekend it went back to normal but the last few days it’s stoped again? Never had a problem in the past. Is something on its way to failing? Or something else? It’s a old gravity system but boiler only two year old, NOT a combi water, tank in the loft area

By gravity do you mean an olde worlde system, pumped rads, gravity HW cylinder, no motorised valves, or fully pumped, open vented? Former unlikely as most modern boilers wouldn't like it.
But I don't see how cold weather could cause loss of HW either way.

 

[gaz1250]

Fully pumped, open vented system I believe, the boiler is only 2 year old. It’s works on a motorised valve for hot water or heating. It maybe not cold weather related but both times it’s happened it’s been when temp is freezing?

 

[JohnD]

Where is your hot water cylinder, and what colour?

Post some photos, including the pipes, cables and controls around it.

Include whatever motorised valves you can find

Examples

https://www.screwfix.com/search?search=Port+valve+&brand=drayton|flomasta|honeywell_home|worcester_bosch

 

[gaz1250]

In the loft and it’s red i believe, I will get some photos asap. The valve is under the bedroom floor so not accessible at the moment, odd place I think

 

[fixitflav]

Fully pumped, open vented system I believe, the boiler is only 2 year old. It’s works on a motorised valve for hot water or heating. It maybe not cold weather related but both times it’s happened it’s been when temp is freezing?

Sounds like Y-plan, but that should give HW, or CH, or both, so if HW is called on the programmer, you should get it. Maybe worth giving HW more time on the programmer. If you had HW on 24/7 I doubt you'd notice much difference in gas usage. Assuming you have a cylinder-stat, of course.

 

[gaz1250]

Yes y plan sounds right, not sure if the cylinder has a stat or not

 

[JohnD]

I've seen a case where the cylinder was constantly calling for heat, even when it was not being heated, resulting in the cylinder coil draining heat from the cylinder and losing it to the radiators overnight. IIRC it was caused by faulty switch in motor head.

 

[fixitflav]

Yes y plan sounds right, not sure if the cylinder has a stat or not

Be unusual if it didn't, easy enough to check.