14 ensuite rooms, 3 x 300 litre unvented cylinder's, BOILERS ????

[hickings]

hi, I have been asked to finish a guest house which has 14 unsuite shower rooms. the old builders and plumbers have been kicked off for being too slow. the owner just wants it all finished now.
there is a 28mm hot feed, 22mm secondary return and a 22mm cold all already go to each room which I have pressure tested already. the incoming mans is a 50mm feed.
there will be just four radiators in communal areas.
all rooms will have air conditioning for heating/cooling.
they want 3x300 unvented cylinders which I will have no problem linking up.

PROBLEM
they want 2x 24kw Worcester Greenstar 24i System Boiler, with a low loss header.
i understand the owner wants two boilers linked together one for back up.

my issue is i think they are over kill for 3 cylinders and 4 rads

is there a better way to link the two boilers without using a low loss header and without multiply pumps as there is not much heat output needed. its not a cost thing.
i just wanted to here anyone else's suggestions?

 

[Killy Bing]

If they want it and are willing to pay, whats the problem?

what are the cylinders?

if they were oso super series each one would pack a 24kw coil!!

 

[TBServices]

14 bathrooms will deplete the cylinders in no time, so you ideally want the full KW allowance to aid fast recovery.

 

[Howsie]

28mm don't sound big enough to me but then again I'm full of morphine at the moment

 

[Roger Welton]

28mm deff doesn't sound big enough, and I'd be looking at Andrews type water heaters for such a large demand, 14 guests all getting up in the morning at roughly the same time put some load on the system.

 

[hickings]

I agree 28mm don't seem enough for me i am optimistic, I would of preferred to re design the whole layout but with plastered walls and already spending £350,000 on old builders he wants to make this work.
I was going to fit 3 x megaflo,
thanks for the reply, I suppose it would worth doing just for the fast recovery.

 

[Roger Welton]

2 x 24kW won't equal quick recovery on 3 x 300l Megaflows IIRC the coils can absorb 20+kW each

 

[hickings]

What would you fit Roger?????

 

[Roger Welton]

Andrews water heaters

Andrews Water Heaters and renewable heating solutions

They have a nice sizing app on the site somewhere

 

[IDCHAPPY]

28mm don't sound big enough to me but then again I'm full of morphine at the moment

Pass some here

 

[Dotty]

Andrews water heaters

Andrews Water Heaters and renewable heating solutions

They have a nice sizing app on the site somewhere

I agree, I've just commissioned an ecoflo 380/980. A nice bit of kit with recovery rate from cold of about 15-20 minutes.

 

[Ermintrude]

I would in the face of others suggest two Jumbo 800 ACV of course. LLH means that alternate low density heat can be figured in, bio mass ect. With all those bathrooms I would be suggesting waste water heat recovery - uses heat left in drains to heat cold incomming 10c is a massive saving in 1600l.

Also with LLH means that the cylinders can be used one at a time or both when fully occupied. 4 rads can be dragged of LLH. Wouldn't use wb pap. Ur gonna need some beef!

 

[Killy Bing]

I would in the face of others suggest two Jumbo 800 ACV of course. LLH means that alternate low density heat can be figured in, bio mass ect. With all those bathrooms I would be suggesting waste water heat recovery - uses heat left in drains to heat cold incomming 10c is a massive saving in 1600l.

Also with LLH means that the cylinders can be used one at a time or both when fully occupied. 4 rads can be dragged of LLH. Wouldn't use wb pap. Ur gonna need some beef!

Pair of intergas 36/40's running the two nearest en suites each.....

 

[Ermintrude]

Wouldn't like to comment on intergas as never touched one. Vogue 40c probably for me if I was going down combi route? Prefer 3 no logic 30 systems

 

[Howsie]

Sit down and do your calcs for the heating, hot water, loading units/pipe sizing and tell them what they should have in place to cater for such an installation.

This will highlight the gap between what's been installed versus what should have been installed.

It sound like a small domestic plumber had had a go at this and was clearly out off his depth.

Tip: Don't let his problems become yours.

 

[happyflyer]

Hicking,

There are too many ifs and buts here, I would get someone to have a quick look at it for you, for instance the 50 mm incoming means nothing if its only 0.5 bar, there are lots
of pitfalls, where is the job. As a few have said the 28 mm for 14 showers etc sounds a little light, if you want to allow for a lot of diversity, then be it on your shoulders.

Normally with this size of a project you would have a break tank on the GF with large storage and a booster set H/C then the mains does matter too much as long as it can fill
the tank and there you have some built in diversity with storage and backup if the mains falls over.

Don't let the client start pushing you where you don't want to go, if it doesn't work you will be the one that doesn't get paid.


Best of Luck Tony

PS you need to take care how you pipe up the three Mega flows the pressure drops need to be equal on the secondary side

 

[Ermintrude]

Give

Shaun Helme (head of UK sales) 07887758602 a ring at ACV he will direct you to local bod and thy will fully spec out the system
.

They do an Andrews type heater also.

The jumbo can be cascaded


Sorry original comment LLH or reverse return .

 

[happyflyer]

Spot on Ermi about LLH or RR.

 

[Killy Bing]

The more i think about it. 300 litre megaflows arnt suitible, even three of them!! You need the recovery rates of an acv.

 

[happyflyer]

Still, KB I think you can get nearly 100 kws of heat into three MF, thats going to take two 40 CDi banging away, it needs a design engineer IMO

Cheers

 

[Ermintrude]

Cram. 240kw into to 800 jumbs

 

[chris watkins]

Cram. 240kw into to 800 jumbs

Just remind us Ermi, how many shares do you now hold in ACV ???? LOL

 

[chris watkins]

Hi hickings
Have you agreed to take on the design liability for this project, if yes, what PI insurance do you carry? You can always get a third party (consultant) to carry out a design review (client pays for) which both of you can agree on works required, then you can concentrate on the install. If not, then don't get involved in the design but put this in writing along with any concerns you may have on the proposed / already installed.

300i Megaflo coil = 24.5 kW (x3 = 73.5 kW) with 2x24kW boilers recovery of 70% will be around 42mins with full 73.5 available recovery would be around 28mins.

 

[happyflyer]

Well said Chris , spot on, he still needs to think about that 50mm MCWS will it do the job ??? looking down the hole in the end of the pipe won't tell him!!!

Tony

 

[happyflyer]

If you start converting this project over to high output gas water generation and reduce the storage, you may be in danger of running out of
gas, it will need a bigger main to drive these units, holding water in storage does not load up the gas main as much, we don't know what the gas main
size is, too many questions and not enough answers, he needs to come back to us with more details.

Tony