combi boiler to temporarily feed a power shower.

[TeaAndBiscuits]

Hi all,

I currently have a gravity fed hot water system, with a Gainsborough PS1200 power (pumped) shower in the upstairs bathroom.

I'm currently refurbing the downstairs shower room and in the process will be replacing the gravity system with a combi boiler (and fitting a mains pressure shower mixer). Once this is complete I'll start on refurbing the upstairs bathroom and will fit a either mains pressure shower there too or maybe an electric shower.

Question is: in the time between getting the combi installed and finishing the downstairs shower, is it OK to temporarily run the power shower upstairs from the combi? Could I just fit pressure reducing valves in the hot and cold feeds to it?

edit: OK, I know it's illegal to pump mains. Hypothetically speaking though, would this work for a week or two?

 

[Hot&Cold]

Hypothetically speaking though, would this work for a week or two?

some instructions for generic built in pumped mixers.
1. DO NOT Connect to the rising mains supply pipe.

2. DO NOT Use with combi boilers or an unvented system.

so its a no,although have seen it done. With differing results.

 

[muggles]

Not advisable - it's not designed to take such pressure and is likely to go pop in the middle of the night (these things always happen in the middle of the night...)

 

[dilalio]

(these things always happen in the middle of the night...)

A bit of excitement at least cos nothing else happens at this time, after 30 years of sleeping with the SWMBO... Except perhaps burglary, or a fire

 

[jeff the gasman]

Yep. I’ve known it last long term. Fit a pressure equalising valve instead.

 

[TeaAndBiscuits]

OK thanks all,

I suppose instructions will always say 'DO NOT connect to mains pressure' because the pressure will be too high, but they can't say '...without fitting a pressure reducing/equalising valves' because it's not allowed anyway.

jeff, why would an equalising valve be more appropriate? Isn't the hot and cold near enough the same pressure on a combi system? And both too high?

 

[jeff the gasman]

OK thanks all,

I suppose instructions will always say 'DO NOT connect to mains pressure' because the pressure will be too high, but they can't say '...without fitting a pressure reducing/equalising valves' because it's not allowed anyway.

jeff, why would an equalising valve be more appropriate? Isn't the hot and cold near enough the same pressure on a combi system? And both too high?

Thought you was using low pressure cold that’s all.

 

[TeaAndBiscuits]

Alright, little update on this.

Finally got my combi installed. Faced with the choice of picking up a cheap mains pressure mixer to temporarily fit in the upstairs shower, or a couple of pressure reducing valves to fit in the feeds to the existing power shower I did what anyone who knows me would predict I would do.

Nothing.

Just connected the new mains pressure feeds into the system and turned it on. Works fine. Now, my mains pressure is barely 2 bar so who knows how it would fare in an area with higher pressure but for now it works. As long as it keeps working for a few weeks, happy days.

So for anyone with the same question arriving here by search - just crack on and connect that power shower up, what's the worst that can happen?