No idea with what type of system i will require for a 6 bedroom/bathroom house

[Amar]

Hi all, I'm a home owner/investor looking to pick some brains of knowledgeable heating engineers and plumbers.

I have just purchased a house, currently a 1970's style 3 bedroom 1 main bathroom and downstairs WC property. currently using a 24kw Worcester combi boiler

I am looking to convert it into a 6 bedroom, 6 en suite house.
The issue I have is, I've had a plumber come and give me a price. He is suggesting to have 2x electric showers and the other 4x mixer showers, sinks and kitchen sink plus the radiators off a 35kw combination boiler.

I'm not a plumber but this seems like a bad idea. I have a combi boiler at home and the pressure is horrible if someone is washing dishes downstairs whilst another person is in the shower. I am happy to have 2 electric showers if the electrician thinks its ok so potentially it may only need to supply 4/5x mixer showers

Would type of system would you recommend for this amount of bathrooms if the water pressure was good. These are the systems I have read about but im unsure of what would be right/efficient system without running out of hot water all the time.

I will in time be getting quotes of local engineers but I'm trying to inform myself a bit first to make sure what should be fitted is correct rather then being palmed off with the easiest thing.

storage combi?
thermal store?
vented system?
unvented system?
Are there any other types that would suit this type of layout?

what kind of costs are we talking per system if there were 15x 700x700 radiators.

Boiler could stay in the kitchen and any of the above systems have a tank in the loft or the possible other location would be under the stairs but again I had the image of needing something like 500l tank for 6 bathrooms. Would this be able to fit in the loft or under stairs? or do they have to be situated together?

Thanks, all comments welcome including Sod takes

 

[ShaunCorbs]

Hahaha bin that plumber off combis won't do two outlets let alone 4 haha

Two 300l unvented cylinders and secondary return if you have the space

Cost wise your best option would to get a few quotes

I have a feeling you would need to upgrade the boiler as well

But you do need a fair bit of space if you do plan to put the cylinders in the loft have a word with a structural engineer (you might need to beef the loft supports up)

 

[Harvest Fields]

I would say that maybe a conventional boiler and not a combi. With 2 unvented cylinders if you have the capability. But that also depends on how many baths you are fitting. Anybody else with any ideas?

 

[Amar]

Thanks for your input guys. Yeah you should have seen the face I pulled when he sid a 35kw combi. ha

Space is abit tight as I'm squeezing in another 3 bedrooms out of the property even converting the garage so the only space I have really is under the stairs, which isn't that big, the loft or split the larger main bathroom into 2 and use half as tank location.

There aren't any baths, just 800x800 shower trays. small basins, toilets and the kitchen sink. washing machines are off cold water. I think?

 

[Adam1312]

I agree with the points above, unvented cylinders and a system boiler if space isn't low, keep in mind you can buy horizontal cylinders, this may be the best option if you have a low loft space, side by side installation. Secondary hot water circuit is a must and also make sure you get the plumber to work out the correct pipe size, the flow from the hot outlet of your cylinder needs to be able to cope with the majority if not all your showers operating at the same time, at xmas for example or Monday mornings!

I can see his point in make 2no showers electric if they are only for people to use every now and then

Your cold mains supply will need to be considered as the incoming pressure and flow rate may not be sufficient to cope with your demand and performance expectations

 

[Amar]

well, tbh, the rooms will be rented to working professionals and they wont know each other. so I'm guessing/hoping they shower everyday so the electric showers should be in use daily.

Do you guys think you could get a 500l tank in a 1.5 x 1.5m space? or is that size tank overkill?

Thinking of using the old airing cupboard for the tank rather then the loft. I don't fancy having to brace the loft with steels or anything? Do you think having the tank upstairs is safe and not too heavy for having on the 1st floor joists?

What kind of flow rate should it need to be coming into the house? does it need to be 22mm plastic pipe? If it was just 15mm pipe or lead pipe can I get a builder to install 22 plastic pipe from the house to the road?

 

[ShaunCorbs]

I would get a 32mm water main installed

And where are you located?

 

[sammathias]

Do you guys think you could get a 500l tank in a 1.5 x 1.5m space? or is that size tank overkill?

probably need that space for pipework alone let alone the tank. Dont think you can get a 500l domestic tank...id say a 300l just for showers and hot taps would be ample tho.

 

[ShaunCorbs]

probably need that space for pipework alone let alone the tank. Dont think you can get a 500l domestic tank...id say a 300l just for showers and hot taps would be ample tho.

That would supply hot water for about 14-16 mins to depleted

 

[sammathias]

That would supply hot water for about 14-16 mins to depleted

If all showers where used at same time for 15minutes...

 

[sammathias]

Sorry shaun. I understand now. By the sounds of it tho he hasnt got space for one 300l cylinder let alone 2

 

[ShaunCorbs]

If all showers where used at same time for 15minutes...

Yea and then an hour and half ish for re heat

 

[ShaunCorbs]

Sorry shaun. I understand now. By the sounds of it tho he hasnt got space for one 300l cylinder let alone 2

Yea he could go instant eg Worcester green spring but pressure is key

 

[sammathias]

Yea he could go instant eg Worcester green spring but pressure is key

How did you suggest 14-16minutes?? Surely all depends on supply and flow rate of showers etc. I means. Decent mixer showers deliever like 14l/min...

 

[ShaunCorbs]

How did you suggest 14-16minutes?? Surely all depends on supply and flow rate of showers etc. I means. Decent mixer showers deliever like 14l/min...

On an 300l unvented cylinder

4 showers each limited to around 10lpm

So that's 40 lpm so half that for a mix of hot and cold so that's 20lpm ish

300l divide by 20 gives you around 15mins at full load

Then approximately an hour and a half re heating depending on boiler loading

 

[Amar]

I would get a 32mm water main installed

And where are you located?

I am located in Coventry but the house being purchased is located in Telford. is there anyone on here that is local and registered to install unvented systems?

 

[Amar]

Yea he could go instant eg Worcester green spring but pressure is key

What is a Worcester green?? yeah pressure may not be very good but again, if we were to change to main water pipe coming into the house???

 

[Amar]

Thanks for all your comments guys. really is appreciated. who said plumbing was easy! ha So from what I gather I would definitely need a 500l tank or 2x 250-300l tanks? for 4 showers?

I was speaking to a family member of mine in London who has 250l tank unvented system, they have just 1 large shower cubicle shared between 4 members of his family, 2x older teens and both parents and he did say there has been occasions where the tank has gone cold ( I think he said it was mainly because someone had turned the hot water off) but they would have to wait well over an hour to have hot water again

 

[Adam1312]

A correctly designed system should not be going cold, takin into consideration I don't know what's else the they have on a system a 250L cylinder for one shower does seem excessive for me, I base my calculations on a average a Shower using 80L max

I think you need to pay for a trusted qualified engineer to make a site visit and design the system properly

 

[Chuck]

Thanks, all comments welcome including **** takes

Such systems need to be designed and installed rather carefully by someone who specialises in 'small hotel' type properties. Things like usage patterns and also how much you are willing to pay for behaviour such as 'never' runs out out hot water vs 'very rarely'. Your first plumber clearly doesn't have a clue.

Same goes for wiring, you need a sparks who understands the the usage pattern.

Make sure you have thought about ventilation. Six showers can put a lot of humid air into the building and if the ventilation isn't up to snuff you'll have major damp/mold problems.