Loft conversion hot water problem

[Tim Jones]

Hi. I’m having a loft conversion done in the Uk. My builder has made the connection for the hot water to the loft but since he has done this my hot water in the rest of the house is not getting hot. I have a combination boiler and the water gets to say 37 degrees ish but not hot hot for washing up or a nice hot shower. It always got hot hot before the new connection.

I’ve shut off the water to the loft and the water goes back to normal ‘hot hot’.

The builder has connected very close to the boiler (first spur connection) directly above boiler after the pipe rises to left of boiler and makes a 90 degree turn to the left. What I’m wondering is this simple a bad spot as hot water rises so I’m getting a loft of heat loss? If we connected not at the highest point of this pipework might it make a difference?

On photo green pipe is new spur to the loft. Red pipes are old hot water pipes.

Any help appreciated!

Tim

 

[SimonG]

Your problem is letting a builder plumb.

 

[Tim Jones]

Your problem is letting a builder plumb.

No doubt but I still need to solve it. I will get my plumber round but looking for some possible vibes if there are any out there!

 

[ShaunCorbs]

Probably the shower is cross feeding or a mixer tap

 

[Tim Jones]

Probably the shower is cross feeding or a mixer tap

Thanks. Sorry can you explain that more? Do you think there is some sort of loop they have made by mistake in the loft? I think everything up there is a dead end and not flowing at the moment (it’s only at first fix) no taps or shower connected yet.

Thanks again.

 

[ShaunCorbs]

Could be yes follow the pipes they shouldn’t be joined together

 

[Timmy D]

Close the cold water inlet valve on the boiler, do you still get water out of the hot taps? If so, you’ve got a cross over.

 

[Tim Jones]

Close the cold water inlet valve on the boiler, do you still get water out of the hot taps? If so, you’ve got a cross over.

Thanks. Did exactly that and the issue was fixed. My ‘builder’ seems sure he did something wrong in the shower unit. I don’t understand it but it’s a grohe shower mixer and he seems sure he put did something wrong that means it allows cross flow.

Thanks all.

 

[Timmy D]

Grohe Rapido shower box? The connections have to be correct as specified in the instructions to prevent problems. They’re very specific depending on what outlets are being connected.

Thanks for the update.

 

[Tim Jones]

Grohe Rapido shower box? The connections have to be correct as specified in the instructions to prevent problems. They’re very specific depending on what outlets are being connected.

Thanks for the update.

It’s a GROHTHERM PERFECT SHOWER SET + TEMPESTA. Sounds right. My builder has taken advice from his plumber mates so it sounds like they have told him what he is done wrong. I assume nothing that could be permanent?

Thanks.

 

[Timmy D]

When this happened, I assume that the bathroom was in first fix stage. The shower valve (blue Grohe box) was mounted/connected but the actual valve/chrome controls where not currently connected.

I fit these. Following the install instructions, once, you’ve connected the pipework to the box, you need to install a plastic dummy test valve.

Then you turn the water on to ensure no leaks and flow from the outlets.

If you were in first fix (before tiling), it’s likely that once tested, the outlet connections were capped during tiling.

If the above is correct, I then reckon the dummy valve wasn’t removed and the inlet bungs installed in the shower box. You install these bungs (one for hot and one for cold). Once bungs are installed, you reinsert the dummy valve and close up the box. This allows the water to stay turned on until tiling complete/valve installation.

However, if after testing, the dummy removal/bung install wasn’t completed, the valve box provides a link between the hot and cold feeds.