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Combi, Storage Combi or electric shower?


Rachieble

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We're about to renovate our old house to rent it out. It will have three bathrooms when its finished. The house currently has a combi boiler, which I'm aware isn't great if two people want showers at the same time. This wasn't a problem for us but probably will be for tenants when there's 5 adults all trying to get ready for work in the mornings so I will have to make some changes to the current set up. There is no space for a hot water tank/megaflow anywhere in the house so I'm looking into other options. As I see it, our choices are either a new storage combi boiler (which will be about £2000 plus installation), or changing at least 2 of the showers to electric showers (about £350 each plus installation). Our water pressure is good. I can't find out very much info about storage combi boilers anywhere so I'm struggling to work out whether this would be a good option and whether they would potentially cope with 3 showers and a dishwasher running at the same time (as a worst case scenario). I'd love to hear some thoughts on the options or whether there's another idea I've missed? 

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I find it unfathomable that a house big enough for 3 bathrooms does not have a cupboard or a loft space that will fit a hot water tank.

 

You can NOT do 3 electric showers (unless you have 3 phase supply) even 2 is pushing it.

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2 minutes ago, ProDave said:

I find it unfathomable that a house big enough for 3 bathrooms does not have a cupboard or a loft space that will fit a hot water tank.

 

You can NOT do 3 electric showers (unless you have 3 phase supply) even 2 is pushing it.

I see you live in the Highlands! This is a London semi detached house where space is at a premium. It will be rented as an HMO with en-suite bathrooms in the bedrooms. There is no airing cupboard. The loft has been converted to bedrooms. There really is no space for a tank, even if you can't fathom it. 

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41 minutes ago, Rachieble said:

I see you live in the Highlands! This is a London semi detached house where space is at a premium. It will be rented as an HMO with en-suite bathrooms in the bedrooms. There is no airing cupboard. The loft has been converted to bedrooms. There really is no space for a tank, even if you can't fathom it. 

sounds to me you need to loose about 1m x1m in one of the bedrooms to have a suitable size tank for all the house 

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9 minutes ago, scottishjohn said:

sounds to me you need to loose about 1m x1m in one of the bedrooms to have a suitable size tank for all the house 

I don't want to keep harping on, but a system boiler really isn't an option, there really is no space, including in the bedrooms. So, now i've said that again, can we maybe move on to the other options? Such as storage combis? 

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Look up Canetis Superflow.  It basically either a 25 or 50 litre vessel that sits upstream of a combi boiler, to improve the performance of a combi boiler.

 

These vessels can sit below the boiler or be wall mounted.  Image shows the large and small versions

maxresdefault.jpg

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1 hour ago, Rachieble said:

I don't want to keep harping on, but a system boiler really isn't an option, there really is no space, including in the bedrooms. So, now i've said that again, can we maybe move on to the other options? Such as storage combis? 


What size is your cold supply to the house and what pressure have you got ..? That is your limiting factor, and you need to ensure you’ve got decent flow before you worry about heating it. 
 

Storage combi boilers are big beasts - where do you plan to install it ..? 

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4 hours ago, CalvinHobbes said:

We will be doing a new build with 4 electric showers

 

OK some figures...

 

8kW is about 35A

10kW is about 45A

 

So 4 of those would  be way over 100A single phase that many houses are limited to. In fact I think many houses only have an 80A fuse in their nominally 100A supply.

 

I'd like to see the figures for a house with ASHP, Electric Shower and Car charger. 

 

Personally I like a better shower/ better flow rate than an 8kW can produce.

 

 

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3 hours ago, Rachieble said:

I don't want to keep harping on, but a system boiler really isn't an option, there really is no space, including in the bedrooms. So, now i've said that again, can we maybe move on to the other options? Such as storage combis? 

 

My choice would also be a system boiler and 300-500L tank. Perhaps with the boiler mounted on wall over the tank. If that's really not possible...

 

Storage combi are just regular combi with small tanks built in. They help boost flow rates but only as long as the tank allow. With three showers going that wouldn't be long.

 

Think I'd try and find a high power combi or possibly two small ones.  Let's say you are happy with the flow rate from a 10kW electric shower. Then a combi to power three would need an output of at least 30kW. So I'd look at something over 30KW and check what flow rate they say the DHW side can deliver. Or perhaps 2 showers on the combi and one electric? Or you can measure the flow rate from your favorite shower and work out what flow rate you need for two or three of those and check the boiler can deliver that and more.

 

Then you also need to check that the cold mains supply to your house can deliver it. 

 

Then check the CH of the boiler is adequate for heating the house. I'd also look for a fully modulating boiler.

 

I'm not a plumber or heating engineer.

 

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12 hours ago, ProDave said:

I find it unfathomable that a house big enough for 3 bathrooms does not have a cupboard or a loft space that will fit a hot water tank.

 

You can NOT do 3 electric showers (unless you have 3 phase supply) even 2 is pushing it.

 

You can do as many electric showers as you like, as long as only one runs at a time...

 

Garo do a CU for the Irish market for exactly this purpose.

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12 hours ago, Rachieble said:

I don't want to keep harping on, but a system boiler really isn't an option, there really is no space, including in the bedrooms. So, now i've said that again, can we maybe move on to the other options? Such as storage combis? 

you still will need space for a tank  no matter what - 

look at dimensions of a tank big enough to store water for 6 people having a shower -

maybe you are trying to squeeze too much in .

what is the floor area of your   of your  on suites - are they already built  or is this you planning 

using shower cabinets will save alot of space .

I have an on suite that I built in a fitted wardrobe space+ 500mm  and its 2m x1.5m with toilet  900x900mm shower cabinet and hand basin etc

 

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1 hour ago, dpmiller said:

 

You can do as many electric showers as you like, as long as only one runs at a time...

 

Garo do a CU for the Irish market for exactly this purpose.

And how do you stop more than one being used in an HMO?  you can get a relay that disables the others when one is in use, then you will just get constant complaints "the shower does not work"

 

I am also intrigued by the layout, there was mention of showers in the bedrooms.  How have you dealt with the electrics re a "room containing a shower" if the shower is really in the bedroom rather than a separate shower room.

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35 minutes ago, ProDave said:

I am also intrigued by the layout, there was mention of showers in the bedrooms.  How have you dealt with the electrics re a "room containing a shower" if the shower is really in the bedroom rather than a separate shower room.

The shower rooms are in the bedrooms. 

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On 19/11/2021 at 20:10, Rachieble said:

I don't want to keep harping on, but a system boiler really isn't an option, there really is no space, including in the bedrooms. So, now i've said that again, can we maybe move on to the other options? Such as storage combis? 

 

what about outside ? 

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