Can I fit a pump to Aqualisa Visage?

[Rp88]

Hi there, any help appreciated!

We've bought a Aqualisa Visage shower to replace our old one, however, have realised it's one without a pump!

Can we just buy a shower pump and attach separately, and if so, does it need to go before or after the digital unit?

We have a cylinder boiler in an airing cupboard and cold water tank in the loft room directly about it

Thanks in advance x

edit: really trying to read into and understand it all, thinking about going for a 1.5 or 2 bar pump with twin impeller, assuming it has to be installed before the digital unit?

 

[muggles]

Yes it would be a twin impeller Universal/ negative head pump installed before the unit. Alternatively just get a pumped digital control unit and sell the unpumped one - there's quite a market for them for people who are changing from a low pressure to high pressure system. It'll be cheaper than buying a pump & bits to fit it https://www.ebay.co.uk/itm/Aqualisa...p2349624.m46890.l6249&mkrid=710-127635-2958-0

 

[Rp88]

Ah, Thanks you! The thing is that when we looked it up, the pumped version is double the price but a separate pump you can get for around £100. So thinking that will be the best option.

 

[muggles]

You'll not get a negative head / universal pump for £100, the cheapest I can find after a quick scout round the net is £280. On top of that there's the Surrey flange & associated connections for the cylinder, tank connector for the loft tank, potentially additional pipe, isolation valves etc etc to sort out.

You can buy that pumped processor, sell your non pumped one for about £200 and save yourself both money and installation faff

 

[Rp88]

Oh right, I was under the impression from what I was reading that we just need a positive head, because the pump wouldn't be level or above the cold water tank. Our digital unit box is in the airing cupboard next the the hit water cylinder, the cold is located in the loft room directly above it

 

[muggles]

The pump always needs to be below the cold water tank even with a negative head pump. It's the vertical distance between the base of the tank and the shower head that is important. However with the digital shower processors there's quite a lot of resistance to flow so you won't get enough water running through a positive head pump to activate it, hence the need for a universal type.

 

[Rp88]

The visage says it will take 7 bars of pressure, so our thought was, get a new pump (majority are positive and have read most common), fit it so water just gets pumped through for more pressure to come through the shower.

When we turn the shower on its very low pressure, and then after a while fiddling about thinking it was an air lock, we realised it's because our old visage had a pump and this new one doesn't (mum didn't realise and bought it as was on a deal).

Can't really understand why we'd need to change anything to fit one to the digital bit?

This is what I read, which describes our system:

"The most common heating system used in the UK is a gravity fed system.

This system normally features a cold water tank in the loft and a hot water cylinder tank in an airing cupboar

This is called a positive head system because the cold water tank is positioned 600mm higher than the shower, so water flows downwards via gravity."

 

[muggles]

External pumps work differently and are of a different design to the internal one found in pumped digital processor units, hence the need to make alterations to accommodate one. If you try to lob it on to the existing pipework it'll almost certainly suffer from cavitation and give up pretty quickly, and as I've said before it's unlikely you'll have enough flow running through a positive head pump to start it running reliably, hence the advice to fit a universal type.