SAP says ideal logic combi and electric shower in 3 bed semi with 2 baths. Will it work?

[Jsnodgra]

Hi,
I'm a house builder and am putting together a spec for some new build semis. They're 1200 sq ft with 2 bathrooms, one main with shower of bath and one ensuite with just shower. A system boiler and tank means I fail the SAP test without some other expensive alterations. If we have a this logic combi 35 with trv's and one zone it passes. My worry is not enough hot water. If I put an electric shower in the ensuite maybe fed from a storage tank, is this the way to do it? Or is there a better way (using the same boiler)
Any help would be great. Thanks in advance
John

 

[ShaunCorbs]

If you want to use a combi boiler then feed the main bathroom with this and use and electric shower in the second on

Or even better fit a normal heat only boiler and unvented cylinder

 

[Jsnodgra]

Thanks for the answer.
Cylinders don't pass the SAP test (in this instance, not all). Is an option having the electric shower in ensuite fed of a storage tank. My worry being there's only so much water coming in. Or will that not work as the storage tank filling is the same as it shooting straight out of the shower head??

 

[ShaunCorbs]

Thanks for the answer.
Cylinders don't pass the SAP test (in this instance, not all). Is an option having the electric shower in ensuite fed of a storage tank. My worry being there's only so much water coming in. Or will that not work as the storage tank filling is the same as it shooting straight out of the shower head??

That's not really the best option (fed from a tank)

May I ask why cylinders don't pass the sap test ?

 

[Jsnodgra]

don't really know to be honest. But sat with the SAP assessor this morning and combis are viewed within the sap system as much more efficient. I guess you only heat water when you need it. I could make a system work but we'd be looking at putting 150mm insulation in the walls and not 100mm. The cost of this means i really need to find a solution with the combi.

 

[ShaunCorbs]

Your only option would be electric shower in the second bathroom

Best speak to your sparky to see if this is possible

 

[Jsnodgra]

Your only option would be electric shower in the second bathroom

Best speak to your sparky to see if this is possible

It's possible, but would it work?

 

[ShaunCorbs]

It's possible, but would it work?

What do you mean Would it work ?

 

[Jsnodgra]

What do you mean Would it work ?

if you turned both showers on, having just shampoo' d your flowing locks would you get a significant drop in pressure, or would a new water supply usually cope with both demands?

 

[ShaunCorbs]

Depends on your incoming main flow and pressure

 

[Jsnodgra]

Depends on your incoming main flow and pressure

Hmmmmm. Which I won't know until I build the houses. From everything I'm reading I'm not feeling a lot of love for a combi and electric shower combination. I just hoped some kind of storage tank could feed the electric shower so the combi (and incoming main) was only really doing the one bathroom.

 

[ShaunCorbs]

You should know the water board should be able to tell you approximately

 

[Meady]

Surely if you would have the flow rate for an unvented cylinder you would have good enough flow for a combi?

 

[Rightjob1]

Cant you have a storage tank feeding a pump to boost into the combi and have your electric shower off the tank also?

 

[ShaunCorbs]

Cant you have a storage tank feeding a pump to boost into the combi and have your electric shower off the tank also?

You would need a massive tank tho but can be done

 

[Scott_D]

Storage combi or high output combi and put flow restrictors on all outlets

 

[Chalked]

Thanks for the answer.
Cylinders don't pass the SAP test (in this instance, not all). Is an option having the electric shower in ensuite fed of a storage tank. My worry being there's only so much water coming in. Or will that not work as the storage tank filling is the same as it shooting straight out of the shower head??

Hi
pressurised cylinders are allowed, but you have to make alterations elsewhere. Better having a happy customer , than one complaining about poor system performance.
You just have to do other things.
Better insulation.
Weather compensation
Flue gas recovery, all jump you back up. You could fit a combi and a pressurised cylinder. Combi to do kitchen and utility. And cylinder to do the bathrooms.
One builder I work for says that we pump vaillant weather compensation on the system. This gets your sap a higher score. I have one in the lockup, which we fit and only put power to it, so it looks like it works. Once passed we move it to the next house.
I know it’s not ideal, but customers can’t fathom out how the thing works.

 

[Yo8Gas]

Storage combi or high output combi and put flow restrictors on all outlets

Have fitted a few Glow-worm Energy 35C Store on a few new builds all have past saps as long as you fit a weather compensator!

 

[ShaunCorbs]

Have fitted a few Glow-worm Energy 35C Store on a few new builds all have past saps as long as you fit a weather compensator!

I believe they've stopped making the stores

 

[Yo8Gas]

I believe they've stopped making the stores

Energy 37 Store | Glow-worm
Glow-worm Energy 35 ErP storage boiler including flue | Plumb Center

 

[king of pipes]

Atag do a 34 kw and a 39kw IC Economiser combi with weather comp and flue heat recovery built in not cheap but would satisfy saps could maybe have one electric shower incase of failure worth a look. Cheers kop