Change loft tank for unvented cylinder

Bendy_House

robatwork said:

What exactly is your pressure and flow rate in l/min?

We have a massive Megaflo but the incoming pressure is about 1.5 bar and by the time that's gone to the loft where the cylinder is, it's probably about 1 bar. It's really not enough to get a really good shower and the pressure at the taps is adequate but not great. 

Sounds like the wrong choice for your circumstances, then.

Is there any way you can improve the incoming? Eg by a new supply pipe? Or - and this will work - you can fit a pumped accumulator such as a Challis which will store your mains water under pressure, and release it to your unvented at whatever rate you require.

It will need space for installation, tho', and around £1k.

Bendy_House

Section62 said:

Bendy_House said:

Since your intention is to seemingly try and keep going, using as little water and energy as possible until you finally swap to a combi, then the leccy shower (5) might well be the best option. This means you'll be keeping the existing vented cylinder for all other hot water uses - kitchen tap, etc. - so it'll still need topping up with heat. You can add more insulation to this to help keep the hot water in.

I'd like to better understand the logic of this.  How does using peak/single rate electric to heat water via an electric shower whilst keeping a tankfull of gas-heated toasty-hot water standing by - but unused - work out to use less energy overall?  And the difference in water consumption is?

It's barely logical, Cap'n. It was just a suggestion given GWS's circumstances; what is one of the simplest and cheapest ways to provide what they need until they go 'combi'?

Of course, that brings us to 'combi vs unvented' again :-)

I also thought the pumped shower unit would be a goer, until it seems the stalwart Triton T40i is no longer made. Alternatives sadly seem very costly.

(Edit - the T40i ain't the one I was thinking of, that I fitted 25 years ago for someone. The original had both H&C feeds so could blend the temp. It was also ELV so had a transformer in the ceiling - nice and safe. Are there any alternatives to this these days?!)

rubble2

Bendy_House said:

Section62 said:

Bendy_House said:

And they'll fire up whenever you run any tap.

Only if installed by cowboy plumbers or dodgy DIYers who don't know what they are doing.

Ok, then - they'll fire up whenever you open up any tap in the bathroom.

We have two shower pumps, one for the en suite was already installed when we moved in, the other for the main bathroom I installed myself. Neither of them 'Fires up' whenever you open any tap in the bathroom.

Bendy_House

rubble2 said:

Bendy_House said:

Section62 said:

Bendy_House said:

And they'll fire up whenever you run any tap.

Only if installed by cowboy plumbers or dodgy DIYers who don't know what they are doing.

Ok, then - they'll fire up whenever you open up any tap in the bathroom.

We have two shower pumps, one for the en suite was already installed when we moved in, the other for the main bathroom I installed myself. Neither of them 'Fires up' whenever you open any tap in the bathroom.

In which case they serve only the shower and nothing else in the bathroom, I presume?

That is indeed an option for GWS too, but it's only one option amongst a few. Like all the options, it comes with a few possible negatives as well as its pluses.

Eg, unless the pump also supplies the whole bathroom, their current poor flow will only be addressed in the shower. But if it's fitted to also supply the whole bathroom, then it'll in theory fire up every time a tap is opened?

GWS seemingly has a shower attachment which is connected on to their bath taps. Good chance a shower pump will make this unusable, so they'd also likely need to fit a proper shower mixer. That should be ideal, but adds a further cost - ~£500-ish?

rubble2

Yes indeed, our pumps are dedicated to supply a thermostatic shower mixer exclusively, I have never come across anyone using a separate pump to increase pressure to the whole bathroom.

Section62

Bendy_House said:

Ok, then - they'll fire up whenever you open up any tap in the bathroom.

Section62 said:

Only if installed by cowboy plumbers or dodgy DIYers who don't know what they are doing.

------------------------

Bendy_House said:

It's barely logical, Cap'n. It was just a suggestion given GWS's circumstances; what is one of the simplest and cheapest ways to provide what they need until they go 'combi'?

Of course, that brings us to 'combi vs unvented' again :-)

Obviously it will depend on the layout of the house - where the existing supplies/services run etc - but on the face of it, any option which involves running both mains water, and a sizeable (multi kW) electric cable, into a room which doesn't have them already isn't likely to be what I'd call simple or easy.

And that's without checking whether the consumer unit has the spare capacity to take the additional circuit/load.

£200 for all that seems a somewhat optimistic starting point unless you are very lucky.


Then if you do switch to a combi, all that has been installed for an electric shower becomes redundant.

It could work out cheaper, but I'd need a lot of convincing before I'd sign on the dotted line if a plumber was trying to 'sell' me that option.

Section62

rubble2 said:

Yes indeed, our pumps are dedicated to supply a thermostatic shower mixer exclusively, I have never come across anyone using a separate pump to increase pressure to the whole bathroom.

You could have a whole bathroom or whole house pump if needed, but then that wouldn't be a shower pump.

And if the pressure was so bad that a pump was necessary on all the taps, its unlikely anyone would complain too much if the pump switched on when they wanted water to come out of a tap.


Your setup sounds just like what the OP needs... as a solution for the short term, if not permanent.  It's really odd that the plumber didn't have the plumber didn't put this forward as the preferred option.  Unless there is something about the situation they know about which we don't.

Bendy_House

With the shower pump option, from what I understand from a previous GWS comment, their shower attachment is fitted on to the bath tap spout. So it would make sense to factor in either a separate wall-mounted thermo shower mixer, or replace the bath taps with a shower 'deck'.

Probably worthwhile, because it could also be used with whatever ultimate option they go for.

Grundfos make (or used to) a 'home booster' pump which was based on their common CH circulating pump with an added flow switch. The lovely thing about this was that it adds just a nice smooth ~0.75bar boost. One person I know who went for this (one on each supply, H&C) was really impressed as it gave a 'natural' response when a tap was opened or the shower used - it was just as tho' their CWS had been raised a few metres! (The drawback was that their plumber didn't install it correctly - it can only be aim upwards, or something - and they soon burned out...)

robatwork

Bendy_House said:

robatwork said:

What exactly is your pressure and flow rate in l/min?

We have a massive Megaflo but the incoming pressure is about 1.5 bar and by the time that's gone to the loft where the cylinder is, it's probably about 1 bar. It's really not enough to get a really good shower and the pressure at the taps is adequate but not great. 

Sounds like the wrong choice for your circumstances, then.

Is there any way you can improve the incoming? Eg by a new supply pipe? Or - and this will work - you can fit a pumped accumulator such as a Challis which will store your mains water under pressure, and release it to your unvented at whatever rate you require.

It will need space for installation, tho', and around £1k.

Yep it was wrong and I've been through all the options. New supply would be about £3k and I looked into an accumulator. In the end I got a slightly smaller showerhead which gives the impression of a more forceful shower for the same pressure. It's all "adequate"!

grumbler

Bendy_House said:

robatwork said:

What exactly is your pressure and flow rate in l/min?

We have a massive Megaflo but the incoming pressure is about 1.5 bar and by the time that's gone to the loft where the cylinder is, it's probably about 1 bar. It's really not enough to get a really good shower and the pressure at the taps is adequate but not great. 

Sounds like the wrong choice for your circumstances, then.

Is there any way you can improve the incoming? Eg by a new supply pipe?

A new pipe can increase the flow rate, but cannot increase the pressure.