amateur....any help appreciated-combi and rennai water heater

[Elli]

Hi there

I wondered if you could help? I'm currently piping up the central heating for my Mum and she's already got the combi boiler a while ago which is an ideal vogue 40kw (so she is out of time to return).

We're on a very limited budget as its a big renovation which is why we're doing the piping ourselves with the intention to get a professional to do the boiler connection/ gas and commission. My dad's a retired gas man with 2 bad knees (recently replaced) so hes been advising/ teaching along the way but hes away so I've tried to scour the internet for a solution to this problem.

My mum has a guest side of the house with 2 en-suite bathrooms which I guess will be used intermittently and in the loft she has the intention of making a self contained flat with bath/ kitchen which will be used more frequently.  I realised the combi will not cope with hot water for all these rooms + my mums own bathroom/ kitchen so I'm thinking of piping up for a rennai water heater to provide the hot water demand for the guest rooms/ loft.

I can see the heater has a 22mm cold inlet/ 22mm gas inlet and hot outlet but I have some Q:

can the 22mm cold inlet be branched before entering (I guess I'm asking this for both the combi and water heater)?? This is the scenario......

The cold has got to come from the mains, travel about 3m and then be branched in 22mm for main bathroom, ......travel about another 3m then a T- .....one branch travel about 1m and then enter the combi and the second branch travel about 1.5m then a T.....one branch will go to supply cold to ensuites/kitchens etc....and the final branch will enter the water heater?

do the inlets into the water heater have to be in copper or be in barrier pipe?

I would really appreciate any help-you really helped me before with my cast iron radiator problem :/ don't you just love old houses!

Elli

 

[oz-plumber]

From what I can gather, you will end up with 4 bathrooms and 3 or 4 kitchens.

Are you sure that the incoming water mains are able to cope with the possibility of say 3 showers running at one time.

Whats the incoming mains pressure and flow rate.

Too many variables pop into my head when reading your post to give you any accurate advice.

40 kW combi boiler and rinnai water heater + other gas appliances - thinking you will need around 400 mj/h gas supply. Is there adequate gas supply available. Have the gas pipes been sized correctly for the appliances to work?

Don't take offence, but I think you're completely out of your depth on this one.

 

[Elli]

thanks for the reply/information. Mains pressure was not something I had considered. It will be:

1 bath/ kitchen running off the combi
2 ensuite (intermittent use), 1 bath, kitchenette running off water heater

All the gas pipes/ flow return have been run initially in 28mm dropping in size towards the end of each run.

I have decided to do a continuous run from the mains to the combi/ water heater and branch later in the run. Probably we are out of our depth but we have been since we started this renovation :S

Unfortunately needs must and doing our best on a limited budget and always seeking advice and getting qualified sign off/ building control-just need to get mums side done so she can move out of our side-for my sanity more than anything

thanks again

 

[rpm]

I`m thinking you are best talking to whoever you have lined up to sign it off tbh.

 

[ShaunCorbs]

Just a tip you can't install any pipe that carries gas unless your gas safe

Sorry to say

 

[jtsplumbing]

Just a tip you can't install any pipe that carries gas unless your gas safe

Sorry to say

Think he has done it already ! Water supply could be a problem, this property should have been converted to unvented hot water system. Flat needs its own independent system if its going to be rented, and he needs to look at how it's going to be controlled, would be better to sell the combi and get a proper system installed

 

[SteveWannadoGas]

Think he has done it already ! Water supply could be a problem, this property should have been converted to unvented hot water system. Flat needs its own independent system if its going to be rented, and he needs to look at how it's going to be controlled, would be better to sell the combi and get a proper system installed

I think Elli :smiley2: might be a "she".

 

[rpm]

I think Elli :smiley2: might be a "she".

We don`t discriminate gender here.

 

[Scott_D]

Have you asked your dad these questions?
Surely he would know about flow rates etc

 

[ShaunCorbs]

right answer to first question

yes the can but all depends on incoming pressure and flow rates (whats your incoming supply)

but if your water heater requires you to have a pressure reducing valve before it enters the heater run any balanced outlets / showers after this (so the water is the same pressure as the hot)

and copper would be the best bet

just a question where are you located?

 

[Elli]

Hi everyone-thanks for the replies and I am a 'she'

I always leave the gas to the gas man including all the gas pipes. I just meant the flow and return had started in 28mm.

If we rent the rooms/ flats it will only be on a short-term basis as its quite a touristy area so maybe on the room to let scheme just to generate some income for the renovation. Alot of the time the rooms will be for family staying which is why we wanted to keep them part of the main house system.

We didn't want to do an unvented system as we had heard some bad safety reports-weren't they banned until the 90's/ until the EU made us have them-? don't want the house to go bang ......I know there are probably lots of safeguards now though.

The water heater was mainly because my mum had the combi already and had read in terms of energy etc the water heater may be more efficient to cope with the extra hot water demand?

I think I will leave the installation engineer to do the mains water pipe as well as I am not sure how to work out the pressure. We are based in Castleton, derbyshire.

Thanks again for all the replies-i do appreciate it.

 

[joni os]

We don`t discriminate gender here.

Can even be ambidextrous.