Is it cheaper to heat water with immersion or gas?

[Deleted User]

What does running it at 55C do? Why do you not want it to condensate? Are the rads still adequately hot?

The efficiency improvement from a condensing boiler comes from having a low return flow temperature > 56C

wittynamegoeshere

Dolor said:

What does running it at 55C do? Why do you not want it to condensate? Are the rads still adequately hot?

The efficiency improvement from a condensing boiler comes from having a low return flow temperature > 56C

Greater than or less than?

Apodemus

wittynamegoeshere said:

mksysb said:

wittynamegoeshere said:

Snookie12cat said:

RobM99 said:

As an aside, is your cylinder insulated?

Yeah, brand new Megalow Eco so it should be the best it will ever be right now. 

I'm intrigued, why do people have hot water cylinders installed these days?  Was a combi-boiler considered as an option?

I fundamentally don't get the purpose of heating a vast amount of water every day just in case you might need it then leaving it to go cold if you don't.

Because when your combi breaks down, you'll have no hot water until it is fixed.  With a tank you have a backup immersion heater.

  Conversely diverter valves on cylinder systems seem to also fail quite regularly and it's at least as complex to fix, probably more so I don't think there's an obvious winner as far as reliability goes.

Yes, motorised valves have a finite life and all will eventually fail.  I currently look after two houses with system boilers. 

One has a 22 year old valve, which recently failed in the closed position.  All I had to do was manually open it until I sourced a replacement head for the valve.

The other was installed in 1969 (just at the time of the moon-landing!) and has never yet caused any problem!

[Deleted User]

Greater than or less than?

Oops - finger trouble. Delete ‘>’ insert ‘<‘. Thanks.

k_man

Alnat1 said:

Our heating comes on at 6.30 and the tank is set to heat 8.00-8.40. I'm no expert but it seemed to me, if the boiler was heating the tank when the house was up to temp. it might use a bit less gas as it was already warmed up. 

That my theory too, although the benefit (I think) is less the house being warm (will likely only be a few degrees), and more the boiler and pipes etc being up to temp.

k_man

k_man said:

Alnat1 said:

Our heating comes on at 6.30 and the tank is set to heat 8.00-8.40. I'm no expert but it seemed to me, if the boiler was heating the tank when the house was up to temp. it might use a bit less gas as it was already warmed up. 

That my theory too, although the benefit (I think) is less the house being warm (will likely only be a few degrees), and more the boiler and pipes etc being up to temp.

Another thought, if the HW is on for a very short period, it will work in reverse, and take heat out of the hot water tank, until the system reaches the current tank temperature.
I suspect this is a very short period though.

macman

A modern tank that is properly insulated loses very little heat, and very slowly. For 6 months of the year, that (minimal) lost heat serves to warm the house anyway. So it's not inherently more expensive.
Many properties are unsuitable for a combi, whether because they have two baths/showers that might be used simultaneously, or because they have inadequate water pressure and/or mains gas flow.
It depends on your particular requirements.