Limited hot water in winter

[Rincewindwiz]

Traditional 80s set up: Ideal classic gas boiler, hot water, tank separate pumps for CH and Hot water
It all works just fine in the summer
Come the winter I can get barely 2 - 3 inches of water in a bath before it goes tepid
If I leave it for 5 minutes I can get a further inch maybe so it is just about possible to have a bath by topping it up every 5 minutes.
But why cant I get a tank full of hot water in the winter - or at least enough for a decent bath - in htre winter when I need it?

 

[ShaunCorbs]

How long do you have the boiler on timer wise for hot water ?

 

[Rincewindwiz]

Boiler Hot water is on permanently. Only turned off when I go away for at least one night

 

[Chuck]

Based on your description, it seems likely that the domestic hot water thermostat is incorrectly set so the hot water is being stored at significantly below 60°C. Another possibility is that the pump that circulates water from the boiler through the domestic hot water cylinder is not working effectively.

Use a suitable thermometer to measure the temperature of the hot water as it comes out of the tap. It should be 60°C or just below.

If you have a hot water cylinder it should normally be sufficient to have it heating for an hour or two at night just before you get up.

If the above suggestions don't solve the mystery, please provide some more details about the system (boiler model, tank size, pump models, etc.) and maybe a photo of the tank and its pipework.

 

[Rincewindwiz]

In desperation last night I read the boiler manual. It does say 2turn the boiler thermostat knob up to 5 or 6 (flow temp 77-82) in the winter from 2 or 3 (flow temp 60 - 66) in the summer" so I did that last night

Today, (hot water on but boiler not alight) the water out of the bathroom tap is initially around 50 - 52 but soon drops off (which is consistent with 2 - 3" of water in the bath). Water out of the kitchen tap same temperature but very milky

Picture of hot water tank plumbing attached

 

[ShaunCorbs]

That’s a thermal store heating has to stay on constant

Eg that tank needs to have the boiler fired constantly else the hot water will go cool

When it goes cool does the tank still feel hot at the top eg you can feel from where there’s no Insulation around the pipe

 

[Rincewindwiz]

thermal Store: Yes I had always assumed that was the case but, as the heating is always on, it is unlikely to be the cause of my very seasonal problem. Turning up the temperature on the Boiler has improved things slightly but there is still the period of hot water followed after 2 - 3 mins by less hot water

 

[ShaunCorbs]

But does the boiler fire / turn on when you run out of hot water ?

 

[Rincewindwiz]

Oh yes. see Original Post
I run the hot water for a bit; the water out of the tap gets cooler. I turn the tap off and wait 10 minutes then I get hot water again for 1 -2 mins then the water out of the tap gets cooler and . . repeat
i can actually hear it firing up.