Changing over to a combi in a bungalow.

[bernardgreen]

instant hot water where frequent hot water

A cylinder provides that ( unless it has been emptied ). Frequent hot water drawn from a combi in small quantities can be less efficient than a well insulated cylinder if the heat exchanger ( from flame to water ) has a large thermal mass to heat before any heat reaches the water. A significant amount of water has to flow before any heat reaches the water. One reason why a small store of water is kept hot in some combi boilers. Wastes a bit of heat as the store loses heat and has to be re-heated but wastes far less water. Apparently on a metered water supply this waste of gas rather that waste of water can be overall less expensive for the home owner.

 

[PullerGas]

Don't see why not. 24kw combi, sufficient to heat almost every household, matched for power output to large percentage of cylinders, instant hot water where frequent hot water needed (kitchen sink), almost always a stocked appliance. Have carried out this type of installation few times

Couldn't agree more Dan. 24KW Combis are the most common boilers bought in the U.K. therefore they're cheap & very reliable appliances.

The problem with this forum; people with no experience, very little knowledge & frankly wrong/dangerous advice control this forum. The Google Warriors like Bernardgreen.

The price of a combi boiler has changed very little in 20-25 years.

 

[dilalio]

Op: There are pro's and con's to ALL systems. If you are tight for space and have good pressure/flow then a decent combi will serve you adequately. If going over from a conventional system with stored hot water, you will get to learn and live with new and different quirks!
One thing worth mentioning is to change your toilet inlet valves to the high pressure inserts as they will now be mains fed - this will stop them nicking so much of the water when someone is in the shower and a toilet is flushed... same for kitchen mixers - you don't need high flow there!

 

[DP]

Bernard, you have already said you are Problem solver, alternate thinker, Agony aunt with a tool box

Us in this trade do not have endless time, nor able to try out weird science to try and solve a problem. End of the day if an installation fitted by me or some other chap, fails to meet expectations, there are going to be folk who will be upset and out of pocket too.

When you try things in your half century abode, you are privileged to have oodles of time, perhaps not a wife like mine who a while ago threatened to call a heating engineer to fix our system when I replaced a dial room thermostat for a digital programmable one

 

[vulcancontinental]

If you said where the combi was going I missed it. If in the roofspace try for one 36kw with 10 year warranty, 14.6 litres a minute, 10:1 modulation but best of all if in a roofspace remote control with alarms, service reminder, boiler reset all available on the room stat downstaird (and on the app if you've wi-fi). If you're familiar with ErP efficiency ratings the 32kw version will give you an A+ system (the 36kw is 0.3% shy of the 98% needed)

 

[bernardgreen]

Us in this trade do not have endless time, nor able to try out weird science to try and solve a problem.

I understand that, what I find wrong with the industry is that there are heating sales people who sell on the basis of maximum profit. And some installers operate the same way. The losers are the customers who do not get the system that is best suited to their needs.

there are going to be folk who will be upset and out of pocket too.

which does not reflect well on the installer who do take proper care over the selection of the system.

If you're familiar with ErP efficiency ratings the 32kw version will give you an A+ system (the 36kw is 0.3% shy of the 98% needed)

If only 98% was achieved in the average installation. Modern boilers can transfer 98% of the energy produced by burning fuel when conditions are right, in the laboratory the right conditions can be set up for efficiency testing. To set the necessary conditions up in a domestic dwelling is difficult if not impossible to achieve. Hence getting close to the conditions for 98% efficiency requires a lot more thought than "bang a combi on the wall" installers can give.

 

[dilalio]

Bernard: you said it... it's an industry; not an experimental science project!
It's been said before: average customers would not stump up for consultancy design and we would not survive in business by offering it for free. Like it or not, it is market economics!

 

[DP]

Bernard: you said it... it's an industry; not an experimental science project!
It's been said before: average customers would not stump up for consultancy design and we would not survive in business by offering it for free. Like it or not, it is market economics!

Quite true. Do not get involved in doing free quotes people always ask for. On odd accession I have been invited to spec a job, it is rarely accepted. Last one was a Poty Puma, quoted a ideal Vogue. What has been fitted is a cheap boiler that will cost a fortune to repair when things go belly up. Words like "I trust you, I will only get you to fit my boiler, no one else" are soon overlooked when combi bashers come through the door.

 

[PullerGas]

If you said where the combi was going I missed it. If in the roofspace try for one 36kw with 10 year warranty, 14.6 litres a minute, 10:1 modulation but best of all if in a roofspace remote control with alarms, service reminder, boiler reset all available on the room stat downstaird (and on the app if you've wi-fi). If you're familiar with ErP efficiency ratings the 32kw version will give you an A+ system (the 36kw is 0.3% shy of the 98% needed)

A Vokera by any chance??

 

[Agile]

try for one 36kw with 10 year warranty, 14.6 litres a minute, 10:1 modulation but best of all if in a roofspace remote control with alarms, service reminder, boiler reset all available on the room stat downstaird (and on the app if you've wi-fi).

Wow, what a spec for an efficient and versatile boiler!

You would think that everyone would fit them instead of those funny Double Dutch boilers!

Do they top up their own pressure if in the loft?

 

[vulcancontinental]

A Vokera by any chance??

I don't feel it is my place to say just set some sort of datum for the poster.

 

[vulcancontinental]

Wow, what a spec for an efficient and versatile boiler!

You would think that everyone would fit them instead of those funny Double Dutch boilers!

Do they top up their own pressure if in the loft?

None so blind as those who will not see Tony and yes, they can top up the pressure if in the loft but not in the UK as our water regs prohibit that which you should know. It is perfectly possible though. Personally a gauge and filling loop downstairs is a perfect substitute.

 

[vulcancontinental]

If only 98% was achieved in the average installation. Modern boilers can transfer 98% of the energy produced by burning fuel when conditions are right, in the laboratory the right conditions can be set up for efficiency testing. To set the necessary conditions up in a domestic dwelling is difficult if not impossible to achieve. Hence getting close to the conditions for 98% efficiency requires a lot more thought than "bang a combi on the wall" installers can give.

No, you need to understand the (ErP) Energy Related Products Directive a little better Bernard although I could have been a little clearer and written 'package' efficiency and not used the term system.