Single impeller pump ( mixer shower)

[Andyh]

hiya fellas ,
Been given a bathroom spec and it includes a universal single impelled pump to run a ( hot side)mixer shower valve... and been toto connect cold side into mains...? Is that asking for problems.. i.e. Unbalanced supplies

 

[Riley]

In short yes. I’d not be happy unless by some fluke the mains pressure matched the pump exactly. I’d push for a properly installed twin

 

[Andyh]

Thanks, thought about adding a pressure reduced valve and set at 2bar to match pump etc ... probably saves upsizing storage tank ...?

 

[Riley]

That’s ok until you get pressure fluctuation when all the neighbors get up/get in and want a shower. What incoming static and dynamic do you have

 

[Welder]

Most importantly, it's not very safe. The potential imbalance can seriously impact the ability of the shower valve to respond to temp fluctuations as effectively. Normally with a balanced supply they respond with a second.

Personally I'd not fit one - end of. Why? As above PLUS when performance goes it will be YOUR fault for fitting. Cynical? Possibly, but tinged with donkeys years of realism...

 

[Welder]

Thanks, thought about adding a pressure reduced valve and set at 2bar to match pump etc . probably saves upsizing storage tank .?

If you don't upsize the CWS you may find warranties are invalid! #AnyExcuseTheseDays

 

[Andyh]

ok thanks I'll explain this to bathroom company and customer... , dual impeller pump and bigger cws is required
Thanks fellas

 

[Welder]

ok thanks I'll explain this to bathroom company and customer... , dual impeller pump and bigger cws is required
Thanks fellas

If you look at EVERY manus website, they will clearly state that CWS must be doubled for any pumped HW system. It also clearly states that the take off for the cold must be lower that the feed for the HW tank for safety reasons.

 

[Andyh]

Sorry fellas but bathroom companies said their fitters use the cold main and salamander say it's fine , so I'm gonna fit the single impeller and get it in writing that any problems is their baby

 

[Ben-gee]

If the shower will accept unbalanced supplies and has fail safe shut down if either supply interrupted, you will be fine. I have come across this setup many times and it works well.
Whole house hot from Monsoon 3bar single, cold from mains.

 

[Andyh]

Ok thanks Ben-gee

 

[SimonG]

Don't understand this.

You fitting this?

It's a bodge, wouldn't care who was saying what. It's a bigger cold tank and balanced feeds.

 

[Welder]

Don't understand this.

You fitting this?

It's a bodge, wouldn't care who was saying what. It's a bigger cold tank and balanced feeds.

I just stopped reading cos I thought it was just me!

 

[Andyh]

Sorry I thought salamander might have an idea of their pump design, I will ring them and relay your concerns

 

[Riley]

They will know their pump but they have no idea of the property and the set up that’s for the pro (you) to spec

 

[Andyh]

Fair one pal , i will ring salamander tomorrow and suggest it's a " bodge " and see if they have a solid concrete spec that supports there claims... I'm the messenger don't shoot