Pricing to replace a vented cylinder with an unvented cylinder (megaflo)

[Piperdave22]

Hello , ive recently gone out on my own, i have been working in the industry 15years now /g3 qualified and i would just like to get some advice from the knowledgable people on this forum! i have done a lot of installing but haven't really got involved with the design as somebody else has done it and just told me where to put things 🤣.
obviously now being on my own im going to be designing the systems etc myself and would just like a bit of guidance if thats ok?

i have a customer that wants to update their vented cylinder to an unvented cylinder to get rid of the tanks in the loft.
there is currently 2 bathrooms:

one with shower basin and toilet.
one with shower bath , basin and toilet
downstairs toilet with basin and toilet
kitchen sink
utility sink

5 people living in the property

they are looking to have a loft extension in the future with an ensuite.

3 bar pressure tested from outside tap with tap open inside
overflowed the weir cup when testing flowrate so over 22l/m

I stupidly forgot to look at the mains when i was there to see the size of the incoming pipework, he's going to send me a picture on Tuesday,
Is there anyway of knowing the size main that feeds the house without going back to the property like building documentation etc ?

the main in the airing cupboard is 15mm that feeds tanks so my thinking is assuming my supply is 25mm blue poly i will need to come from there to the airing cupboard in 22mm as that 15mm will be to small ? would that be correct?

what size cylinder would you recommend?

what manufacturers would you usually go for?


also what other things do i need to think about in regards to pricing it ie electrics etc or anything i might have forgot

toilets will need to be changed to high pressure diaphragm / orifices . is there anything else like that i need to think of ??

appreciate any responses!

Dave

 

[ShaunCorbs]

Other than looking what’s at the stop tap no

Correct 22mm to the combo valve ideally not plastic either

300l unless you’re sticking it on hw priority

Gledhill or joule

Is the system a y plan as this will require a bit of extra time but I normally allow for re doing the heating box anyway

discharge is the big issue

ply the back for the expansion vessels

showers might be old and either no nrv or passing nrv also these should be on the balanced supply etc

 

[Scott_D]

Weight of the cylinder
Discharge
Convert to S plan
1 immersion or 2
Is the heating suitable to seal the system
Expansion vessel, fill loop & prv

 

[Piperdave22]

@scott_d @ShaunCorbs massive thankyou for your responses,
its not going on hot water priority so ill go with the 300L theres already a 210litre vented cylinder in there and ill be putting it back in the same position so think the weight will be ok .
system is currently a s plan so will probably keep it that way tbh. discharge is fine as im going to be revamping the bathroom where the cylinder is and im going to run it under the bath and down the outside wall with a grill at the bottom .
both showers will be brand new as im doing both bathrooms that are next to each other.

there is currently 2 immersions but neither of them are wired in , very good point ill allow for that thankyou!
they havent asked for the heating to be pressurised but i can give them that option too as im running a discharge anyways and it gets rid of the header tank for the loft conversion.

thanks again for your responses , been really helfpful! if you can think of anything else then let me know

 

[ShaunCorbs]

You will require a sparkie if the immersions arnt wired / no circuits for them

 

[Piperdave22]

You will require a sparkie if the immersions arnt wired / no circuits for them

@ShaunCorbs yeah thats fine, already contacted him as he will be putting in a supply for a digital processor etc anyways.

what route would you go down if the main is too small ?
accumulator?

 

[ShaunCorbs]

@ShaunCorbs yeah thats fine, already contacted him as he will be putting in a supply for a digital processor etc anyways.

what route would you go down if the main is too small ?
accumulator?

depends on flow and pressure if your getting the required on both out of the main then that’s enough just 22mm from the stop tap to the unvented

 

[Piperdave22]

@ShaunCorbs im getting 3 bar pressure and over 22l//m flow.
i got a picture sent through today and its 15mm copper coming out of the floor for the mains water.
would you enlarge the pipe work from the stopvalve to 22mm and see how it goes or see if an accumulator or flomate etc could be fitted

 

[ShaunCorbs]

I would do 22mm from the stop tap and you should be good aslong as the lpm is correct

 

[Piperdave22]

I would do 22mm from the stop tap and you should be good aslong as the lpm is correct

Its over 22lm so think it should be ok ,ill qoute on that basis then . They have just informed me the the new bathroom is going on the same level now so won't be any pressure loss to another floor .
I'll quote on a new 22mm run from the stopvalve to the airing cupboard
Replacing old 210 vented for 300 litre unvented and electric supply for immersions.
Safety to run under bath and down wall .
Thanks mate really appreciate the help!

 

[Roy_66]

One silly thought I've had on these conversions. If you only do the hot water and leave the heating, you then end up with a header tank in the loft that will hardly have any flow to it. So a long length of dead stub, which is presumably not a good idea? ( Apologies I'm not sure of all the answera here)

So assume most change both systems to pressurised at the same time.

Cheers,
Roy ( very amateur plumber, no qualifications whatsoever )