Towel Rail connected to hot water tank?! And Mixergy Tank any good?

[JohnD]

If it's fitted on the hot pipe, it will impede flow when not runni g

 

[ndoubt]

Ok team - finally got someone in. Recharged air gap in megaflo. Took secondary circulation pump onto a timer that I’ve left off for 12hrs. And installed evohome hot water kit to track temp of water in megaflo. Overnight the cylinder temp has gone from 55deg to 30deg according to my evohome app. Didn’t use any hot water in that time. So frustrating what could I be missing?!

 

[ndoubt]

One thing I have noticed is that the hot water supply pipe from the top of the megaflo is constantly hot .. should that be the case or should it only be hot when hot water is drawn from the taps/shower?

 

[JohnD]

There will be some movement due to thermosyphoning. Lag the pipe which is hot. Isn't there a valve on the return pipe?

 

[JohnD]

Like this

I've had one like that. My preference would be to remove the pump, which will obstruct flow when it is not running

And put a gate valve on the return pipe (to prevent unwanted flow) and put up with the delay in the distant bathroom.

And of course insulate all the pipes.

If you wanted, you could control the yellow pump so it ran when the distant bathroom was occupied, for example with a PIR or off the light switch.

Don't throw away the yellow pump, due to its value.

 

[ndoubt]

I will lag those pipes for sure but surely that wouldnt account for sucha temp drop? that size temp drop suggests cold water is being drawn in? when you say valve on the return pipe sorry not sure what that means? Cheers John!

 

[JohnD]

The pipe goes to the distant bathroom, and returns. Hot water flows into that loop, runs through the pipe which acts as a long thin radiator, losing heat all the way, and returns cooler to the cylinder, to repeat its journey.

A valve on the return pipe will prevent this circulation.

I don't know if hot water is being lost somewhere. You could turn off the supply and see if that makes a difference. I'd expect you to hear it, or see the steam, or notice a humid area.

If the cylinder is constantly being refilled with cold water to make up for a leak, the supply pipe will be winter-cold. If it is not running, it will slowly approach room temperature.

 

[ndoubt]

oh apologies - you mean a valve in the secondary circulation system? ive put the pump on the secondary circulation system on a timer - and i feel no heat at all in that circulation system now which surely solves that issue..

does the hot water coming out of the pipe on the top of the megaflo circulate back anywhere when the taps arent running or does it just sit in the pipe?

 

[JohnD]

oh apologies - you mean a valve in the secondary circulation system? ive put the pump on the secondary circulation system on a timer - and i feel no heat at all in that circulation system now which surely solves that issue..

does the hot water coming out of the pipe on the top of the megaflo circulate back anywhere when the taps arent running or does it just sit in the pipe?

Yes, if that was the trouble. Maybe there is something else? Can you follow the hot pipe and see where it's going?

The pipe coming out of the top of a cylinder is normally hot, it commonly has a horizontal length in it to prevent or reduce convection. I insulate mine very heavily.

 

[ndoubt]

it runs 10 inches vertically then maybe 15 inches horizontally before coming down the side of the cylinder to the floor where it runs off through the house and its hot all the way along.. i'll get it insulated properly this weekend which will help no doubt, but i fear there may be something somewhere drawing that hot water. I did read a threat somewhere about potential issues with 'passing' in shower mixers or mixer taps? Could there be something in that?

 

[JohnD]

Try feeling all the pipes. When no water has been used for an hour or so they should all be around room temperature.

 

[JohnD]

it runs 10 inches vertically then maybe 15 inches horizontally before coming down the side of the cylinder to the floor where it runs off through the house and its hot all the way along.

Ah, that's flow, not convection.

 

[ndoubt]

Try feeling all the pipes. When no water has been used for an hour or so they should all be around room temperature.

yeh the pipe was hot well after an hour of turning the hot water off.

Ah, that's flow, not convection.

any advice on how to find out where is flowing.. wld like to think any leak wldve been picked up on by now after years of it being installed..