Help me spec this job.

[TBServices]

Right. Been to look at a mates parents boiler today.

BG have been to repair, and AR'd their 35kw ferroli combi, due to vert flue in void with no access hatches.

Boiler was leaking badly and I think it's blown their PCB. Anyway, that's beside the point, they want a new boiler, BUT, the house has 2 bathrooms and a shower room, they also say they can't get hot water without choking the taps right down, due to high pressure and flow.

There's room for a system boiler and unvented cylinder in the existing location but the pipework to the boiler comes through the wall from the room behind, hidden behind a false wall, so I can't see how the hot and cold pipework is sized, I'm assuming 15mm from wherever its tee'd off. Nor can I see a way (at the moment) to bring a 22mm cold in, hot out and balanced cold out.

Heating supplies are 22mm, 10 rads and 3 towel warmers all heat up fine.

Going back next week to size up properly. What would you do in this situation? Fit the cylinder on the 15mm supplies and have unbalanced supplies?

Or would you just fit a large combi and restrict the flow down to 18l/m?

They're happy to go with whatever I suggest, regardless of budget, but they obviously don't want their VERY nice house ripping to bits.

 

[Ermintrude]

937...........

 

[TBServices]

If I was going for a big combi, it wouldn't be a 937. Store depletes too fast. I'd be going for the baxi system if I went down that road.

I'd rather go down the unvented route tbh. They have to starve one of the showers of cold water by opening a cold tap full chat to get hot water lol.

The main question is, is a 15mm cold inlet, hot outlet and an unbalanced cold supply going to work? The hot pipework throughout the house could be in 15mm for all I know at this stage.

 

[Nostrum]

Do you need balanced cold feeds to any of the bathrooms?

If the pressure and flow is suitable with the 15mm then you could just connect. Your going to have the same problem with a storage combi anyway though so personally I would do everything possible to find out how it's piped.

Has this combi been in since the house was built or could it have been converted from a cylinder in the past?

Have you got enough gas to run a bigger combi?

 

[Nostrum]

Just seen its a 35kw, but is the gas adequate?

 

[TBServices]

The gas is in 22 and the meter is about 2m away.

There are thermostatic shower mixers in all the bathrooms.

The combi was put in when they bought the house 8 years ago, there was a tank and cylinder in the loft before that. The combi location is so bizarre that it must have been moved from where original boiler was. It's in a sort of entrance hall, right at the front of the house, so I expect we have 22mm hot supply pipework from original airing cupboard location, but 15mm supply pipework to where the combi is now.

 

[Ermintrude]

Guess you could conn the cold to hot and measure dynamic performances at outlets to see if you need to balance?

 

[Nostrum]

No chance of fitting the cylinder back in the original place I take it?

 

[TBServices]

There may actually be a way to balance, but it would mean knocking a few tiles off in the adjacent bathroom where the stop tap is hidden.

It's a really funny old house. Stone walls, different floor levels etc.

 

[Nostrum]

Could you use a P.R.V set to just below the unvented for the entire house?

 

[TBServices]

No chance of fitting the cylinder back in the original place I take it?

No, but tbh that's out of the question anyway, as I'd still need F+R up there, new 22mm cold main, not to mention discharge pipework. Current location is completely ideal, except for the h&c pipe sizing.

 

[TBServices]

Could you use a P.R.V set to just below the unvented for the entire house?

It's a possibility! Again, means knocking a few tiles off though lol

 

[Nostrum]

Out of interest, what about the flue, just cut some hatches?

 

[TBServices]

Boilers dead, they're not interested in keeping it. New boiler will be flued through the wall.

 

[Killy Bing]

Thinking outside the box, putting the pressure reducer before any take off to balance everything and just have the unvented expansion to take up the small amount of cold pipework expansion?

my unventeds are on 15mm supply and work fine but the incoming is great.

How wealthy are they?
are they intending on staying in the property?

you could spec a beast of a combi to go in as you said with the budget.

ACV ? Fit and forget!

 

[Mike Jackson]

How about something like a Viessmann Vitodens 222-F. I've fitted it's smaller brother the 111 and the customer was made up with the performance.

 

[IDCHAPPY]

Not that I've had much experience with them but would a combi with the thermal store like the 937 or the baxi one you suggested or a moucher high flow not be ok? how ofter do all bathrooms get used simultaneously?

 

[TBServices]

They will be staying in the property, there's only 2 or them but they do have regular visitors staying with them.

My issue with putting a PRV on the cold as it enters the property, is the potential for reduced pressure to muck everything up. As it stands the cold round the house is exceptional. Reduce it to 3 bar and the performance from the 15mm might diminish.

ACV and the 222 do look good, but I'm sure in this case they would actually take up too much room, and probably be needlessly more expensive. The space I have to work with is long, but thin. A 450 cylinder would fit just about perfectly.

Another issue is whatever boiler I fit will need to be flued with a balcony kit as the flue will have to terminate within a porch.

 

[lame plumber]

if they are happy with a combi setup and are used to it why change it? Just put a prv on the mains and adjust it as needed to work everything and wack in a nice big intergas 36/40 and advice them to have an electric shower installed as backup if needed.

 

[TBServices]

They're not happy with the combi. It doesn't work lol.

I don't think they'd be too happy ripping off all their marble bathroom tiles to get an electric shower fitted. We're talking by out a period country property here. Not a 3 bed semi.

 

[Ermintrude]

Well then ACV SL and a nice big logic 24system

Not sure about balcony kit . Think logic range is limited .

I hear alpha cb50 may be an excellent choice - that is if your getting a divorce shortly and want to stitch them up!

 

[Killy Bing]

Tb, could you get us photos?

what is the flooring to the boiler area?

Are there any other spaces to remotely put a cylinder?

 

[IDCHAPPY]

Well then ACV SL and a nice big logic 24system

Not sure about balcony kit . Think logic range is limited .

I hear alpha cb50 may be an excellent choice - that is if your getting a divorce shortly and want to stitch them up!

:LOL:
I feel the Alpha love in this post

 

[TBServices]

Flooring is concrete.

I'm going back next week. I'll take some pressures and flow rates etc.

Current boiler location is ideal. Moving further into the house makes everything awkward.

 

[Ermintrude]

Contact mc Donald engineers

01529 611123 or Doug on 07534700821

They can make an unvented any shape and size you want. Even send without insulation to get through door, then you just need to get it lagged with three layers of 25mm celotex.

 

[lame plumber]

They're not happy with the combi. It doesn't work lol.

I don't think they'd be too happy ripping off all their marble bathroom tiles to get an electric shower fitted. We're talking by out a period country property here. Not a 3 bed semi.

you asked for advice, then give stupid repsonses which doesnt help anyone!

 

[TBServices]

Contact mc Donald engineers

01529 611123 or Doug on 07534700821

They can make an unvented any shape and size you want. Even send without insulation to get through door, then you just need to get it lagged with three layers of 25mm celotex.

There's more than enough room for an off the shelf cylinder. Even 2!

 

[TBServices]

you asked for advice, then give stupid repsonses which doesnt help anyone!

What's stupid about it? :s

 

[TBServices]

you asked for advice, then give stupid repsonses which doesnt help anyone!

By the way, I meant the system in general doesn't work for the house, not that the combi is broken.

 

[vern]

It's easy Tom.......but you ain't gonna like it pal

WB 440 OR 550 CDi job done they have 22mm cold and hot connections, but WB did some testing and found with good pressure you can get 50L+ down 15 mm no problem.440= 20L or 550 = 25 L per min

I have done a 550 in a house that has 3 rainforest shower heads, 2 run at once no drop, with 3 it robs the other 2 slightly but they all run together, guy did not want unvented, so it was the only solution, thermal store seems it hold its own with 42KW up it lol........

Plus the Manko's will thank you