plumbing a thermostatic mixer shower

[frosti]

Hi, I need to plumb in a thermostatic mixer shower over a bath. there is no exsisting shower only mixer bath taps.

do I need to plumb in separate pipe from the hot water tank or can I cut into the hot and cold supplies for the bath taps?

Also any one have any advise on sinking a bath into the wall by 30mm each end? oringinal bath is 1640 new bath they want fitting is 1700.

Thanks for your help

 

[pauls]

for the shower i think you will need to cut into the hwc using an essex flange if you go into the existing pipework you wont get the balanced pressure for hot and cold.

 

[Puddle]

Well firstly if you are not fitting a shower pump you do not need to bring separate pipework from cylinder and tank,to a thermostatic shower, however if possible it is good practice to do so, if you have a bath/shower mixer there already run the shower and when temp ok, run kitchen sink, if ok, no problem, if slight temp veriation, fitting a flow restrictor at kitchen sink will help avoid pressure drops at shower, assuming only one bathroom and very rare someone using basin and wc when someone in shower
As regards bath size, you may get away with 40mm at end of bath and 20mm at tap end but then you have tiles and if walls not good, could be coming off wall 4mm, getting very tight
I use to following to options
1. Fit bath at tap end correctly or slightly more into wall but giving enough room for tiling and taps and then recess back end further in wall, then when tiling have last row or two of tiles fitted angled back as required to compensate (obviously you will have to chamfer wall as required)
2.My preferred way when in this situation is do away with taps and order 1700 bath with no tap holes and then you can fit bath evenly into end walls and you can either fit taps in wall (better for very low pressure) or fill bath though combined bath overflow and filler
Or you can just say the new 1600 bath is the same as the old 1700 before we went metric but without air bags and power assisted steering ect ,ect woffle,woffle and will cost a lot less to install

 

[stevetheplumber]

If there is sufficent and equal presure on the bath supplies then yes you can just tee of the bath supplies just make sure you have he right mixer for the preasure you have