Vented system to Combi

[TotalR]

Hi,

So I can get my head around the work involved in this. currently have vented system with boiler in kitchen. Moving to Combi, staying in kitchen. has 22mm gas suuply and condense pipe can go straight out the wall. Hot & cold already in cupboard.

in the airing cupbaord what needs to be done to the Feed & Return here? system is as below but with 2 valves one for heating one for HW.

 

[Aire]

Can't you discuss this with your installer? I'm sure you can understand why we would be reluctant to give out advice on a boiler install to non gas registered forum users.

 

[TotalR]

I could yes. However I want to know now, hence my question and the point of a forumn? I'm not asking anything to do with the boiler (gas). Is the airing cupboard pipe adjustments as per below.

 

[TotalR]

 

[Scott_D]

Heating water going to hot taps?

 

[TotalR]

Heating water going to hot taps?

Edited... Hot feed already in kitchen cupboard.

 

[Stu-B]

what’s wrong with the current set up?

 

[TotalR]

what’s wrong with the current set up?

20plus year old non condensing inefficient boiler with old copper cylinder. Was going to upgrade to unvented and new system boiler but big Combi cheaper and more convenient.

 

[OffshoreGas]

Personally I would seek advice from a few different plumbers, combi boilers may often be cheaper but they come with quite a few drawbacks including:

The on demand nature of the hot water means unless you fit quite a large heat output one you may struggle to run a shower while someone is washing up for example.

Another consideration in loosing your HW cylinder is you are solely dependent on your boiler for HW as you no longer have an immersion heater for emergency use.

Adding renewable heat sources is more complex/limited should you choose to in the next 10-15 years.

Combi boilers are more complex that system boilers, in theory at least the less there is the longer life you're likely to get from it.

Just my 2p/opinion, but I'd always suggest a customer asks for the drawbacks of any system as well as the positives.

 

[TotalR]

Personally I would seek advice from a few different plumbers, combi boilers may often be cheaper but they come with quite a few drawbacks including:

The on demand nature of the hot water means unless you fit quite a large heat output one you may struggle to run a shower while someone is washing up for example.

Another consideration in loosing your HW cylinder is you are solely dependent on your boiler for HW as you no longer have an immersion heater for emergency use.

Adding renewable heat sources is more complex/limited should you choose to in the next 10-15 years.

Combi boilers are more complex that system boilers, in theory at least the less there is the longer life you're likely to get from it.

Just my 2p/opinion, but I'd always suggest a customer asks for the drawbacks of any system as well as the positives.

Thanks appreciate the advice. I have taken all into account, and a 35-40kw chucks out enough water for us. We have good mains pressure also. Given a Combi is around 1500 fitted with 7 years warranty I’m happy it’ll pay for itself as the winter gas bills were extortionate on current set up. I initially was thinking of keeping the system because of said points, however most recent plumber asdvised bigger Combi would be fine.

 

[Scott_D]

Which boiler are you getting for 1500 fitted?
Sounds very cheap

I got got a price for a Vaillant boiler, flue, filter and controls and it was more than 1500

 

[TotalR]

Which boiler are you getting for 1500 fitted?
Sounds very cheap

I got got a price for a Vaillant boiler, flue, filter and controls and it was more than 1500

Baxi 636 I’m looking at. May go down the more expensive route of a worcester/Vaillant but can’t see any reason too right now.

Any responses on my initial question?

 

[OffshoreGas]

Baxi 636 I’m looking at. May go down the more expensive route of a worcester/Vaillant but can’t see any reason too right now.

Any responses on my initial question?

HW obviously comes directly from the boiler and not your tank. You installer will need to make a connection between your existing HW pipework and the new boiler. This may not be ideal as your existing pipework should be deigned to suit the location of your existing tank.

I'd also question where your plumber intends to cap off the HW pipework to your cylinder as dead legs (especially containing wamr water) pose a risk of Legionella.

 

[TotalR]

HW obviously comes directly from the boiler and not your tank. You installer will need to make a connection between your existing HW pipework and the new boiler. This may not be ideal as your existing pipework should be deigned to suit the location of your existing tank.

I'd also question where your plumber intends to cap off the HW pipework to your cylinder as dead legs (especially containing wamr water) pose a risk of Legionella.

Hot water will be connected in the cupboard of the boiler as current hot water to kitchen tap runs through there. Not sure on the dead legs as two bathrooms are either side of the airing cupboard so hopefully not a big run.

 

[Riley]

You won’t get any advice on unvented cylinder plumbing as you need to be G3 qualified to work on and install unvented cylinders

 

[TotalR]

You won’t get any advice on unvented cylinder plumbing as you need to be G3 qualified to work on and install unvented cylinders

I’m not asking for any advice on unvented cylinder plumbing. Thanks for the helpful response though.

 

[Riley]

I’m not asking for any advice on unvented cylinder plumbing. Thanks for the helpful response though.

Apologies posted in wrong thread

 

[sammathias]

Personally I feel replacing a low pressure system to a combi the pipework has already stood the test of time and it is time to fully replace all system pipework! Been to countless installs where there are leaks due to system pressure change.

 

[Scott_D]

Cold into the boiler
Hot water out

Heating flow from boiler to radiators
Heating return from radiators to boiler

Don’t forget the heating filter, flush, chemicals, lime fighter, shock arrestor, additional expansion and boiler plus controls.

 

[OffshoreGas]

Personally I feel replacing a low pressure system to a combi the pipework has already stood the test of time and it is time to fully replace all system pipework! Been to countless installs where there are leaks due to system pressure change.

Wise words, quickest way to find a weakness in a system that’s been operating barely above atmospheric pressure for 20 years is to shove 1.5 bar in it.

 

[Rob Foster]

20plus year old non condensing inefficient boiler with old copper cylinder. Was going to upgrade to unvented and new system boiler but big Combi cheaper and more convenient.

Quite honestly you are probably
much better keeping your existing set up
most modern boilers are all rubbish and the combis even worse, loads of people make loads of money specifying, selling and fitting in reality pathetic units, that will not last
7 years or even less.
That is my opinion ..been in this game many years in all sorts of roles ...Rob Foster
aka centralheatking

 

[TotalR]

Personally I feel replacing a low pressure system to a combi the pipework has already stood the test of time and it is time to fully replace all system pipework! Been to countless installs where there are leaks due to system pressure change.

Had the pipe work replaced recently, was all 8mm micro-bore when I moved in. System has a pump on it at the moment anyway.

 

[TotalR]

Quite honestly you are probably
much better keeping your existing set up
most modern boilers are all rubbish and the combis even worse, loads of people make loads of money specifying, selling and fitting in reality pathetic units, that will not last
7 years or even less.
That is my opinion ..been in this game many years in all sorts of roles ...Rob Foster
aka centralheatking

Just a toss up atm between a very expensive Baxi Solo which works with niggles, or upgrade to Combi.

 

[Aire]

Just a toss up atm between a very expensive Baxi Solo which works with niggles, or upgrade to Combi.

Expensive in what way? Gas usage?

 

[shyguy2005]

Thanks appreciate the advice. I have taken all into account, and a 35-40kw chucks out enough water for us. We have good mains pressure also. Given a Combi is around 1500 fitted with 7 years warranty I’m happy it’ll pay for itself as the winter gas bills were extortionate on current set up. I initially was thinking of keeping the system because of said points, however most recent plumber asdvised bigger Combi would be fine.

Combi conversion for £1500!!! Wow

 

[TotalR]

Expensive in what way? Gas usage?

Yeah was very expensive to run over winter. Given its old and non condensing I guess it shouldn’t of been a shock.

 

[TotalR]

Combi conversion for £1500!!! Wow

Why wow? Days work with £1050 boiler/flue.

 

[Aire]

Why wow? Days work with £1050 boiler/flue.

Love the optimism

 

[Riley]

Way too cheap

 

[TotalR]

Love the optimism

Have 3 prices and boiler sourced

 

[Riley]

Is he flushing the system?

 

[shyguy2005]

Love the optimism

I suppose if the guy works through his lunch lol

 

[Aire]

Have 3 prices and boiler sourced

I'd be very wary of the plumber willing to do a boiler for that price

 

[TotalR]

Is he flushing the system?

Pipe work is about 3 months old with a magnaclean already fitted.

 

[TotalR]

I'd be very wary of the plumber willing to do a boiler for that price

Plumbers**

 

[Aire]

Plumbers**

Have they asked for cash?

 

[Riley]

I’d still be dubious, have they mentioned gas pipe sizing? I’m sorry it’s way too cheap. Are they all gas safe??

 

[TotalR]

Have they asked for cash?

Any other irrelevant, non constructive comments?

 

[Riley]

You’re asking for professional opinion we are giving you professional opinion it’s way too cheap to be a quality job

 

[TotalR]

I’d still be dubious, have they mentioned gas pipe sizing? I’m sorry it’s way too cheap. Are they all gas safe??

Yes. As said gas is 22mm. Why would you think I should pay a plumber more than £450 for a day? Boiler is going in the same place as original and they need to do some alterations in the airing cupboard. Or are you all the 1k a day plumbers/brain surgeons.

 

[Aire]

Given your initial question, and the very cheap quotes, I'm starting to suspect you may be doing alot of the work yourself.

 

[TotalR]

You’re asking for professional opinion we are giving you professional opinion it’s way too cheap to be a quality job

I’ve not asked for any opinion on the price, I’ve employed many tradies over the last 5 years not to worry about it.

 

[TotalR]

Given your initial question, and the very cheap quotes, I'm starting to suspect you may be doing alot of the work yourself.

I’m truly disappointed that you feel that way.

 

[shyguy2005]

Yes. As said gas is 22mm. Why would you think I should pay a plumber more than £450 for a day? Boiler is going in the same place as original and they need to do some alterations in the airing cupboard. Or are you all the 1k a day plumbers/brain surgeons.

So it’s one guy on his own?
What about other materials copper, controls etc?

 

[TotalR]

So it’s one guy on his own?
What about other materials copper, controls etc?

I didn’t ask their arrangements. I have copper and controls.

 

[Aire]

Do You have boiler+ compliant controls?

 

[TotalR]

Do You have boiler+ compliant controls?

Have a hive.

 

[shyguy2005]

Yes he has smart Honeywell trv kit in with that price too.

Do You have boiler+ compliant controls?

 

[Aire]

We're not trying to wind you up, but a combi conversion, (a proper one) isn't a days work. And anyone quoting £1500 for a boiler install is either in desperate need of the work or they're not registering/declaring the work.

 

[TotalR]

We're not trying to wind you up, but a combi conversion, (a proper one) isn't a days work. And anyone quoting £1500 for a boiler install is either in desperate need of the work or they're not registering/declaring the work.

I’m sure you feel you are correct, but I don’t know why you would know more than 3 plumbers that have been in my property and seen it with their own eyes and come highly recommended.

What could possibly take longer than a day? Boiler goes in cupboard, gas already there, condense pipe straight through wall, hot and cold already there. Flow return already there. Airing cupboard, do the adjustments that I don’t know what is done because everyone wants to be a know it all instead of answering my initial question except for the helpful response from Scott.

Again, you must be the 1k brain surgeon?