Accumulator/expansion tank sizing

RichardS said:
Apologies. somehow I missed the temperature data, although I'm still not sure that you'll ever be able to "get more hot water than your calorifier contains." The best you can ever do is get exactly the amount of hot water your calorifier contains .... albeit mixed with more or less cold water. :unsure:

Richard
Click to expand...
If you are aiming for a temperature midway between the temperature of the cold and the hot equal volumes of the two will be required resulting in an effective doubling of the calorifier capacity
 
What's necessary and what's desirable - so often the meat in these long discourses....

When my calorifier crashed I replaced it with one having the required safety release valve and a thermostat to regulate the temperature of water passing onwards into the distribution system, The jabsco pump replenishes an accumulator which is normally about 2/3 full of water with air pressure above it. The pump cuts in when pressure has fallen by a margin - so it's not always jerking on and off - a nice feature to have. I fitted a one way value into the cold supply to the calorifier to prevent unwanted mixing.

The advice I got was to add belt and braces with an expansion tank - the red pressure container with a rubber diaphragm across the middle and an adjustment value on the base. It was easy to cut into the water system and trouble free. I don't believe this is essential but I am reassured to have it.

This arrangement gets a lot of use and works well, either with engine-heated water or from the immersion heater in the calorifier. I commend it.

PWG
 
VicS said:
If you are aiming for a temperature midway between the temperature of the cold and the hot equal volumes of the two will be required resulting in an effective doubling of the calorifier capacity
Click to expand...
Yes .... but that is not what I said. The calorifier capacity is fixed and you will never be able to get more hot water than it contains ..... and hence my second sentence. ;)

Richard
 
RichardS said:
Yes .... but that is not what I said. The calorifier capacity is fixed and you will never be able to get more hot water than it contains ..... and hence my second sentence. ;)

Richard
Click to expand...
What Hoolie said in the first place is correct then. With a 15litre calorifier and a thermostatic mixer he will get 30 litres of hot water.
 
VicS said:
What Hoolie said in the first place is correct then. With a 15litre calorifier and a thermostatic mixer he will get 30 litres of hot water.
Click to expand...
You seem to be taking this too seriously. What Hoolie said in the first place was "Another additional benefit of a thermostatic mixer valve is that you get more hot water than your calorifier contains" and I gave the tongue-in-cheek response that this statement, taken in isolation, defies the laws of thermodynamics.

It's not rocket science ..... although, actually, it probably is. :unsure:

Richard
 
RichardS said:
Apologies. somehow I missed the temperature data, although I'm still not sure that you'll ever be able to "get more hot water than your calorifier contains." The best you can ever do is get exactly the amount of hot water your calorifier contains .... albeit mixed with more or less cold water.

Richard
Click to expand...

The TMV is fitted as an anti scald device, it's a domestic requirement under building regs, which might also apply to calorifiers, but i'm not sure.

If the calorifier hold 30 litres of 85 deg water, that's obviously all you can get out of it (as you say). What the thermostatic valve does is mix the hot and cold at source, so you can have 60 litres of warm water at the hot tap. This is used by calorifier manufacturers as a selling point. But, you can achieve exactly the same by using mixer taps, or even putting equal amounts of hot and cold water in a sink. :)

Different people set their valves in different ways, I set mine to shower temp. My mixer taps require the hot and cold valves to be adjusted to get the desired water temp', pausing whist showering means they have to be set again. So having the hot supply set to shower temp means i just turn the hot tap on, no need for any cold.
 
PaulRainbow said:
Different people set their valves in different ways, I set mine to shower temp. My mixer taps require the hot and cold valves to be adjusted to get the desired water temp', pausing whist showering means they have to be set again. So having the hot supply set to shower temp means i just turn the hot tap on, no need for any cold.
Click to expand...

Yes, that's the easiest solution, as I also described in post 19. However, some people don't like having the thermostatic mixer set to shower temperature, as say hotter water is needed for washing up.
 
You must log in or register to reply here.

Share this page

Top