Mid-Range Large Combi

[GQuigley67]

got a job to price up for a builder, its an extension onto an exisiting house which is quite big on its own anyway they are insisting on a combi, I need to give the builder an estimate so I haven't really done my rad sizing yet as the foundations arent even in yet but trying to judge it myself it seems as if a 35Kw boiler will be on the borderline and may struggle, anyone recommend any larger combis which are in the mid price range ??

oh and there are is a toilet, bathroom and en-suite, for HW you have a couple of basins and a bath the shower is electric.

 

[SimonG]

Are they just asking for combi because they like mains pressure hot water? 180 litre unvented cylinder and system boiler? As an option.

 

[GQuigley67]

nah mate mainly for space I think, they wanted me to fit the combi under the stairs which was extremely tight and no chance of it happening, you would think with such a large extension they would fit in an airing cupboard but they are being a bit awkward space wise, big huge new kitchen but they dont want it in the kitchen so I think its going in the shower room thats all me and the builder could agree on but hes still to put it by the customer

 

[Davinder]

I agree with the above, system boiler and unvented cylinder.

But if they insist on acombi then Baxi do a 40Kw boiler:
Baxi Duo-tec Combi HE A

If they do why do they insist on a combi?

I've never fitted oneof these so I don't know if it's any good.

 

[GQuigley67]

because everyone thinks combis are the bees knees

i was looking at the baxi one, i told the builder i was thinking of a baxi combi but just wondering if anyone else has any recommendations

 

[GQuigley67]

Think I'll go with the Duo-Tec 40 HE, CH Output 34.4 KW Condesing and 32 Kw Non-Condesing and its just under £1k

 

[diamondgas]

Hi GQuigley67,

I installed one of these in a residential home [DLMURL="http://www.idealheating.com/products/istor_he_homeowner.php"]Istor HE Boiler - System Boilers - Ideal Heating[/DLMURL]

Don't know how much space you have....? I know it's an Ideal but hey!

 

[mfgs]

Its just a crappy icos sat on a mini unvented cylinder. Pain in the arse to work on, and they are always going wrong. I have had to replace the expansion vessel on the HW side on every single one I have worked on. Also all the factory fitted joints are shocking. In other words, avoid at all costs.

 

[diamondgas]

Its just a crappy icos sat on a mini unvented cylinder. Pain in the arse to work on, and they are always going wrong. I have had to replace the expansion vessel on the HW side on every single one I have worked on. Also all the factory fitted joints are shocking. In other words, avoid at all costs.

Ooops!! LOL ... Only one I've fitted and it was supplied by the client, their choice. Never been back however and that was over a year ago! Hot water was impresive I thought *shrug*

 

[Billy Bob Bob]

fitted a few baxi duotec 40kw the performance is impressive,just make sure your getting the right pressures at the meter and inlet to the boiler being a atmospheric pre mix burner it will whine its head of if pressures are out

 

[SimonG]

nah mate mainly for space I think, they wanted me to fit the combi under the stairs which was extremely tight and no chance of it happening, you would think with such a large extension they would fit in an airing cupboard but they are being a bit awkward space wise, big huge new kitchen but they dont want it in the kitchen so I think its going in the shower room thats all me and the builder could agree on but hes still to put it by the customer

Ah well, customers always right!!!!!!

 

[doitmyself]

1. How many bathrooms and showers will there be in the house?

2. How many people who could be bathing or showering at the same time?

3. Have you checked the cold water flow rate and pressure?

If the answer to 1 and 2 is more than one and the answer to 3 is less than 20litres/ sec and 1.5 bar your customers will soon complain of slow filling baths, showers running slow etc.

Do they realize that, with a combi, everything is supplied from the one incoming pipe, not just the hot water? So, if someone decides to wash the car while someone else is having a shower, both will notice it - unless the flow rate and pressure is high enough.

 

[AWheating]

If the answer to 1 and 2 is more than one and the answer to 3 is less than 20litres/ sec and 1.5 bar your customers will soon complain of slow filling baths, showers running slow etc.
.

20 litres per second, i dont think you will get the customer complaining with that..... well maybe that the shower took there skin off! LOL

 

[AWheating]

if you had the room you can get a vaillant combi with a pre heat cylinder? is big tho.

 

[Mrs Tara Plumbi]

If size is important I think Rehema Avantarange are the smallest combis but I think the biggest is 35kw.
5 year parts guarantee and Heateam suppport are good points for the customer

 

[SafeGasInstall]

i would go for wb CDI 37 or 42 ,just make sure you pipe size the gas correct as this are monsters when it goes to full max !

 

[SimonJohns]

i would go for wb CDI 37 or 42 ,just make sure you pipe size the gas correct as this are monsters when it goes to full max !

Don't fall for that trap. I did. You don't actually get 42kw of heating

You only get 32kw. I was very disappointed when I just finished fitting both of them and found out. Lucky the system worked even thou it was slightly underpowered.

And make sure gas pipe sizing again


Sent from my iPhone using Tapatalk

 

[tamz]

Gerry what kind of house is it and what size extension are they putting on. +35 just for the heating means a hellava size house and gives you very little choice without geting into other ways.
If they really want to go combi (we all know what we should fit but why try to knock a square peg in a round hole. sometimes we just need to do what is required) Consider the points doitmyself raised.
You say they have a bathroom and en suite so there is a posibility of 2 showers? being run at the same time. How many occupants in the house? An old couple is unlikely to ever use 2 at the same time where a family will at some time. What are they willing to accept and are they willing to compromise? A 30kw may suit a couple but a family will complain.
If you have the room prefferably fit a storage.
Stick to the mainstream of what is being fitted in our area which means (in alphabetical order only) Alpha, Ariston, Baxi (potterton) Vaillant, Vokera Worcester. You have got to think back up here. Veissmann and others may make good boilers but they offer :censored: cover up this way. A 4 day wait for a visit means an unhappy cust who will slate YOU to anyone who will listen.

 

[tamz]

Don't fall for that trap. I did. You don't actually get 42kw of heating You only get 32kw.

You only get 30 and a bit at 80 60 which if we are honest is more than most will be run at.

People just don't get how things should be.

I am seriously considering the pull cord option and not only for old people.
I have recently had a job drive me crazy. Fitted an RF +1 to a boiler swap and they couldn't work it!!!!! We are talking a plus and minus button and just ignore the off and on if you like.
Not only could the old people not work it (i would have maybe allowed them a 2nd visit without a complaint) but their 40?? year old school teacher daughter couldn't work it so another visit.
Then the final straw, the son who is alledgedly an I&C fitter with the council (need i say more? he is that good he allowed his parents to pay me to fit a boiler and he lives 3 miles away) phoned to say he had to open the heating valve manually to get heating! I talked him through the intracasies of how to work a plus button and called round the next day to remove the stat.
Another satisfied customer and i am not kidding. They are really so happy i removed that blight on their lives the old guy even gave me a miniture of Glenfiddich as a thank you!

 

[doitmyself]

If size is important I think Rehema Avantarange are the smallest combis but I think the biggest is 35kw.
5 year parts guarantee and Heateam suppport are good points for the customer

The biggest is the 39C, which has a HW output of 39kW (35C rise @ 15.9 litres/min) and a heating output of 6kW to 33kW. The max heating output can be easily reduced by the installer.

Size: 670mm high; 400mm wide; 300mm deep.

The Parts guarantee maybe 5 years, but it's only two years Labour.

 

[Billy Bob Bob]

You only get 30 and a bit at 80 60 which if we are honest is more than most will be run at.

People just don't get how things should be.

I am seriously considering the pull cord option and not only for old people.
I have recently had a job drive me crazy. Fitted an RF +1 to a boiler swap and they couldn't work it!!!!! We are talking a plus and minus button and just ignore the off and on if you like.
Not only could the old people not work it (i would have maybe allowed them a 2nd visit without a complaint) but their 40?? year old school teacher daughter couldn't work it so another visit.
Then the final straw, the son who is alledgedly an I&C fitter with the council (need i say more? he is that good he allowed his parents to pay me to fit a boiler and he lives 3 miles away) phoned to say he had to open the heating valve manually to get heating! I talked him through the intracasies of how to work a plus button and called round the next day to remove the stat.
Another satisfied customer and i am not kidding. They are really so happy i removed that blight on their lives the old guy even gave me a miniture of Glenfiddich as a thank you!

had a tenant ring up today just moved in boilers a year old performa he,them boiler wont work,me try this,try that no joy gets to site boiler control knob in off position now boilers dont come much easier to use than this one what a mong

 

[doitmyself]

20 litres per second, i dont think you will get the customer complaining with that..... well maybe that the shower took there skin off! LOL

Read this and thought: What's he talking about - you need 20 litres/min if you have two showers going at the same time! Then I read it a second time and thought - I'm an idiot! That's not the first time I've done that!

The problem is you work with litres/sec for boiler flows and litres/min for hot water. Why cant it be consistent?

 

[Mrs Tara Plumbi]

Read this and thought: What's he talking about - you need 20 litres/min if you have two showers going at the same time! Then I read it a second time and thought - I'm an idiot! That's not the first time I've done that!

The problem is you work with litres/sec for boiler flows and litres/min for hot water. Why cant it be consistent?

Hey i read the same thing and thought the same. You are not alone!

 

[GQuigley67]

well the Hot Water requirement is going to be a bath, couple of basins, kitchen sink and only 1 shower which is electric. It's a family of four I said to the builder that I recommended system boiler and unvented but he/they are insisting on a combi so they are going against my recommendation. I only done a rough estimate on the sizing the house is quite big on its own then the extension will be downstairs and upstairs

 

[Mrs Tara Plumbi]

It sounds like a combi is the right thing.
The electric shower is heating the water for the shower.
No one ever has a bath these days so that just collects dust.
The WM & DW require cold water.
They only need hot water for kitchen sink and to wash hands so why would you want a system which stores hot water?
Go for a basic combi which will meet their heating requirements and not a storage model.
Best if pipework can be very short to kitchen sink & cloakroom.

BUT, if they do want a bath that is different, esp in winter.