hot water is lost

[izzy eckerslike]

We have a problem with our system in that when we have a nice hot tank of water it is cooled right down if we then run the central heating, The boiler has flow & return for the heating & also another pair of pipes which heat the water tank.
I can't see why the c/heating pipe needs to go thru the tank as this is what cools the water down, eventually the heat to the water comes back as the radiators get hot. Is something connected wrong with our system & can it be easily altered?

 

[Agile]

It sounds as if its wrongly connected.

As you dont explain the history of the situation or your type of system its difficult for me to guess why its wrong. Certainly pipes dont reroute themselves so its possible if this is a new occurance that the motor valve has failed.

Tony

 

[izzy eckerslike]

hi there, thanks for replying,
The system is fairly old, previous owners were well into DIY botching, I have just been trying to work out what pipes go where & the heating pipes don't go thru the tank as I first thought,
Looking at diagrams on the internet I see that the hot water is gravity fed to indirect cylinder, there are no electric valves in the system,
turning on the heating will drastically cool the hot water in a few minutes & take quite a while to get back hot again if heating is running, presumably the influx of cold water from the rads to the boiler is causing this, on normal systems like this how is this prevented?

vic

 

[Agile]

This will occur on all gravity systems however it rarely causes any significant problems and this is the first time I have ever heard of it.

It does not create a problem because the system rapidly reaches 60°C in say 10 minutes when the rad sizes and flow rate are correct.

I would be interested to know your actual boiler output power and the output power of the radiators and the flow/return differential of the heating system.

That information might indicate why you find it a problem.

Tony