Help with understanding my indirect hot water system, and whether it is efficient for my needs?

Reed_Richards

haste said:

The current arrangement means that the hot taps take a long time for the water to run hot - I would guess 60 seconds on average. 

My house (actually a bungalow) originally had a hot water cylinder in the centre.  Then a previous owner removed it and installed a combi boiler.  But the pipes from the combi, which was at the far end of the building, were fed to where the cylinder used to be then back to the taps.  This made for very long pipe runs and at least 60 seconds and a bucket full of water before a tap would run hot.

Now I have re-installed a hot water tank and also a ("recirculation") pump and extra pipes that circulates hot water around the building and back to the tank.  The pump runs for 5 minutes each hour we are awake and the pipes are very well insulated.  The result is that I get hot or warm water from the taps very quickly, the delay is just from the pipe run from the recirculation loop to the tap.   

haste

QrizB said:

haste said:

Worcester Bosch Greenstar 8000 Life GR8300iW 50 R NG 

That looks to be a 50kW regular boiler (the Combi model number ends "50 C NG").

https://www.worcester-bosch.co.uk/products/boilers/directory/greenstar-8000-life-regular

Thank you for clarifying, I wasn't sure. It does have a hot water symbol that I can turn on, but it's off at the moment, so I assumed it had hot water functionality. 

bagand96

That's a modern water tank and will be well insulated (beneath the thin outer metal layer).

Basically when the water is "on" the boiler will fire and distribute hot water round a loop to the tank which runs it around a coil to heat the water in the tank.  When the tank reaches the set temperature the boiler will cut out (so even though it's set on for 4 hours it's unlikely to run continuously for that long.)

I'd be surprised if you needed the water heating on 8 hours a day.  Try reducing it, say 2 hours in the morning and an hour in the evening and see how you go.  It will be a case of trial and error to see at what point you run out of hot water, depends on how many in your household and how much hot water is used.  But modern water tanks can retain temperature for a decent amount of time.  

If you can find a temperature for your hot water set it for 60 degrees, this is the recommended temperature to avoid legionella but you shouldn't need any higher as it ends up getting mixed with cold anyway for showers/baths/washing up etc.

Using the immersion will be more costly method of heating the water (look at your electricity unit price compared to gas).

Reed_Richards

haste said:

Thank you for clarifying, I wasn't sure. It does have a hot water symbol that I can turn on, but it's off at the moment, so I assumed it had hot water functionality. 

Looking at the manual:

Hot water key: Adjusting the hot water temperature (not applicable for regular appliances)