CH Layout Question

[baggy99]

I'm fitting a new Biasi Riva 26kw Condensing Combi Boiler (well the pros will fit the boiler, but I'm doing the plumbing) and have a couple of questions:

1 - CH will comprise 7 or 8 rads across 2 floors. My plan is 22mm in & out of boiler, 22mm equal Ts to LHS & RHS, manifolds at each end to split into 4 x 10mm, 10mm to & from rads. All horizontal pipework will be above 1st floor ceiling, so downstairs verical pipework will go down the walls and upsatirs verticals will go up the walls. I plan to put verticals in surface trunking for ease of access. Does that sound OK? Comments?

2 - I will need to fit a bypass valve as it will be all TRVs, but where? Immediately under the boiler?

3 - Boiler MIs state incoming mains connection should be 15mm. Is that big enough to cope with combi DHW? There will be a bath but no shower BTW. Current feed is 15mm so I'd prefer not to have to rip it out and replace will 22mm, but it just seemed small?

Thanks

 

[weareleeds]

Why would you even consider a biasi

 

[ChrisR]

Same reason people have Indesit washing machines?

There are about 6 Rivas on their site, none 26kW!
What you're doing sounds OK but talk to the heating guy before you do it. And don't touch the gas or fit the flue.

 

[baggy99]

>> Why would you even consider a biasi

Cos I was offered it at a price I couldn't refuse. I presume you are going to tell me they're c**p? Is so, why? Reliability? Features? Efficiency?

As to the 26kw, that should have said 28kw......

No intention of touching the gas or flue - I know my place !! Just wanted to check the basic CH layout. Presume I don't need motorised valves, etc with a comi? Just pipe in the flow & returns?

And what about the 15mm cold feed - does that sound man enough?

Ta

 

[gas4you]

2 - I will need to fit a bypass valve as it will be all TRVs, but where? Immediately under the boiler?

You will need one radiator without a trv in the room with the room stat to conform to Part L regs, so no need for a bypass.

 

[baggy99]

Just what I needed to know - thanks. Is there anything else in my proposal that would conflict with Part L?

 

[gas4you]

Not from what you've posted. 15mm cold mains should be ok for a combi as well.

 

[Soggy_weetabix]

I was led to believe they had an internal bypass but being biasi I doubt it.

Personally Id bypass the boiler.

Worcestor
Vailliant.

Not Biasi ffs

 

[baggy99]

Thanks Dave, ref the 15mm info

Soggy - yes it has an internal bypass BUT it also says you should fit an external. I think the internal one is for emergencies only !!

 

[Dan Robinson]

A price you couldn't refuse eh?

Then the seller can't wait to get rid of it - or its nicked.

Either way - it is that price for a very good reason.

If this is your own home then I would seriously consider a better boiler - think of going to 32kW as well.

 

[baggy99]

Not really a fair assessment - it was bought for a project which changed direction - all perfectly genuine. I'm still waiting to hear what's so terrible about this boiler?! BTW, its not for my own home - its for a flat I'm refurbing, BUT I will be renting it out once its done, so if its a duff boiler its ME it will come back to haunt. Info pls......!

 

[Dan Robinson]

It's just an inferior boiler sold at close to a loss on the grounds that they'll stiff you for spares.

There's a reason why these things are sold in B&Q type places.

I'm sure its not nicked (was kinda joking there); but my other statements still apply... It was priced for a reason and the seller can't wait to get rid of it.

Reason?

It's a cheap boiler fitted by people who generally (but not always) just want to get a property done as quickly and as cheaply as possible.

Or they don't know the above.


That being said if it is installed properly then the price you're paying for it maybe worth the operational time it'll give you before conking out. just don't throw anymore cash at it. We have in the past fitted budget boilers with realtively few troubles. So to tar everything with the same brush (except Potterton/Baxi ) is probably a little harsh.

 

[baggy99]

Thanks for the warning. If I have time to find another b4 it gets hung on the wall I will do so!

I am also looking at an oil boiler for another project. You mentioned Potterton - are you saying they are rubbish too (cos they are not cheap!!)

 

[Dan Robinson]

They're not cheap 'cos they have to pay all those warranty engineers.

Our order of preference goes:

Atmos Heat Systems (Intergas and Multi's)
Worcester Bosch (if client really wants mainstream)
Veissman (under request)
Vaillant (been a while since we've fitted one though 'cos they went a bit t1ts up).

None are cheap, but as I mentioned earlier. You pay for what you get.

Hope this helps.

 

[Dan Robinson]

Sorry,

Noticed that it was oil - the oinly oil we've done was with the Worcester Danesmoors conventional flues. Big, heavy, simple. Not sure of the oil/efficiency regs though as we are mainly gas (used OFTEC guy to comission); so it might not be allowed now.