High gas usage for boiler.

[stevedurban]

i was told (rightly or wrongly) when it as fitted that they are so super efficient, that it can be left on all the time because they will only really heat when you use the hot water, because the thermal loss is so negligable.

However, your point is very valid that if there are issues, it could be heating all day!

The house would have 2 baths and 1 shower in an evening normally - so from a quick google, thats maybe 90L? tank is 210 - so if we just have the water on tomorrow for 2 hours at 12pm tomorrow, that should cover the day?

 

[John.g]

What is the cylinder stat set to now and what is the boiler temperature (set point) now, does this setting be changed in summer/winter?.

Two baths at 88 Litre/bath? and 45C is equivalent to 123 litrs of cyl HW at 60C so ~ 77 litres at 60C remaining = 128 litres at a showering temp of 40C = 10 min shower at 13LPM.
12kwh required to heat tank from cold so 2 hours should be fine as cylinder stat will cut out boiler anyway??.

 

[Chuck]

Another couple of faults that need to be ruled out:

1. The CH zone valve were letting by when it should be closed. The CH radiator system would then act as a bypass for the DHW cylinder and waste a lot of heat in the process.

2. An incorrectly set automatic bypass valve (ABV) opening when the cylinder is heating.

P.S. Sorry if these ideas have already been discussed; I'm not able to read most of the posts at the moment because everything is covered in adverts.

 

[stevedurban]

What is the cylinder stat set to now and what is the boiler temperature (set point) now, does this setting be changed in summer/winter?.

Two baths at 88 Litre/bath? and 45C is equivalent to 123 litrs of cyl HW at 60C so ~ 77 litres at 60C remaining = 128 litres at a showering temp of 40C = 10 min shower at 13LPM.
12kwh required to heat tank from cold so 2 hours should be fine as cylinder stat will cut out boiler anyway??.

cylinder stat:


Boiler is on 6



We don’t generally touch them all year round.

 

[stevedurban]

Another couple of faults that need to be ruled out:

1. The CH zone valve were letting by when it should be closed. The CH radiator system would then act as a bypass for the DHW cylinder and waste a lot of heat in the process.

2. An incorrectly set automatic bypass valve (ABV) opening when the cylinder is heating.

P.S. Sorry if these ideas have already been discussed; I'm not able to read most of the posts at the moment because everything is covered in adverts.

1) any way to prove this option?
2) here is the external abv




Is there an internal one in the boiler that may need checking.

 

[ShaunCorbs]

Turn the cylinder stat down boiler should go off if it’s heating the hot water

 

[stevedurban]

I’m pretty sure the house is calling for heat almost all day - and just no longer able to get up to temperature. Tado shows in the heat graphs as follows. The darker area shows when the boiler is firing constantly. The medium grey means it’s coming on and off a few times an hour apparently - and the light colour is off (this is heating only!)
The house is relatively well insulated, loft conversion to regs 5 years ago. Cavity wall insulation installed 10 years ago. Double glazed throughout.

When I discussed the issue with tado - they said looking at the graph for how the temperature drops from when the heating is off over night, the house only looses about 3 degrees over night - which he said was relatively good!

So could Chucks opinion that maybe something like a bypass not working properly - causing the water to go round and round instead of to the radiators be an issue?or something along those lines? Pump not pushing hard enough?

 

[John.g]

Can you see the actual boiler temperature from the boiler display to confirm that the high setting 0f 6+ is actually reflected in the boiler temperature.
Also, as suggested above, turn the cylinder stat up if the motorized valve is shut and ensure it opens and turn it down if the motorized valve is open and ensure it shuts.
If the boiler temperature is as high as it might be, 75C+, and if the DHW temperature doesn't feel scalding then a fair indication that its temperature is being controlled to its setpoint of 50C. (should really be 60C, for legionella protection).

 

[stevedurban]

Can you see the actual boiler temperature from the boiler display to confirm that the high setting 0f 6+ is actually reflected in the boiler temperature.
Also, as suggested above, turn the cylinder stat up if the motorized valve is shut and ensure it opens and turn it down if the motorized valve is open and ensure it shuts.
If the boiler temperature is as high as it might be, 75C+, and if the DHW temperature doesn't feel scalding then a fair indication that its temperature is being controlled to its setpoint of 50C. (should really be 60C, for legionella protection).

I tested the boiler stat - the valve was closed - I turned the boiler stat up and the valve opened. As soon as I turned it back down - the valve closed again.

Unfortunately the boiler doesn’t have a display - only the dial.

 

[John.g]

Ok then, the flow pipe from the boiler should be absolutely scalding and you should only be able to touch it for a very short time.