Looking to replace water cylinder which type needed?

JohnD · 24 Mar 2020

hard-work said:
much cheaper to run than your old boiler.

Modern boilers are more efficient than old boilers.

The combi-ness is not what does it. It's the design and efficiency. A modern system or conventional boiler will be slightly cheaper to run than a modern combi boiler. It also has less inside to go wrong.

It is a mistake to think that a modern efficient boiler must be a combi.

HERTS P&D · 24 Mar 2020

Mojo12345 said:
One bath

Which day of the year, we can then work out your birthday.

Andy

hard-work · 24 Mar 2020

JohnD said:
Modern boilers are more efficient than old boilers.

The combi-ness is not what does it. It's the design and efficiency. A modern system or conventional boiler will be slightly cheaper to run than a modern combi boiler. It also has less inside to go wrong.

It is a mistake to think that a modern efficient boiler must be a combi.

I never wrote that. But while we are at it....system boilers will have heat wasting cylinders. Combis are on demand. Then there is the extra expense of space consuming unvented cylinders, complexity and associated controls, etc. BTW, there are stored water combis available, which means a smallish "unvented" cylinder inside.

hard-work · 24 Mar 2020

Mojo12345 said:
One bath

Any high flow combi will do. But you want a quality one. Intergas has been suggested and I would go along with that, with them having only 4 moving parts and built like tanks. The latest range are excellent, the Xtreme, which modulates the gas burner way down low raising efficiency, so have an OpenTherm room thermostat/timer, which ensures the burner modulates to the heat demands of the house. Most of the tme when heating house the burner will be just turning over, unable to hear the boiler.
Intergas Xtreme is excellent:
https://www.intergasheating.co.uk/consumer/products/xtreme/xtreme-36/technical-data/

Modulates down to 3.6 kW with just under 15 litre/min water delivery. Will fill a bath up quick enough..and.. with the low water usage Raindance type of shower heads will deliver two showers simultaneously. But not the bath fill and a shower.

Just make sure the cold water main pipes are fitted properly. With a full-bore main stopcock and dedicated 22mm cold water feed to the combi. At the main stopcock tee off all the other cold water supplies. Put restricters on all the outlets to throttle down low usage outlets to balance the hot & cold system. This applies to all mains fed systems, not just combis. In short ensure all flow/pressure goes to the combi and showers.

Varying prices on the web for the Extreme, so look hard.

Mojo12345 · 24 Mar 2020

Thanks everyone for all the advice

Hugh Jaleak · 24 Mar 2020

hard-work said:
Modulates down to 3.6 kW with just under 15 litre/min water delivery. Will fill a bath up quick enough..and.. with the low water usage Raindance type of shower heads will deliver two showers simultaneously. But not the bath fill and a shower.

Just make sure the cold water main pipes are fitted properly. With a full-bore main stopcock and dedicated 22mm cold water feed to the combi.

Without knowing the OP's mains supply is up to the task, you cannot possibly suggest this.

hard-work · 24 Mar 2020

Assuming the mains water delivery is adequate of course, which is a given. As I wrote it can be improved inside the house by having larger bore pipes to reduce pressure/flow losses and teeing off withe separate cold water line (the whole line can be restricted in flow) with also restricters on H&C outlets, except the shower and bath of course. Washing machines & dishwashers do not need 15 litres/min pouring into them. They can do quite well with just 3 litres/min.

Hugh Jaleak · 24 Mar 2020

Stick to Google, you are once again out of your depth and it clearly shows. Without being on site you cannot possibly determine the quality of the mains supply. This is a DIY forum and the OP is asking for professional advice. For all we know the OP has a shared Lead supply, which drops to a trickle if demand is made elsewhere, making all your ideas useless and/or pointless. It needs someone to survey the job and offer the best option for the individual circumstances.

There may even be little wrong with the current system that a flush and service wont sort out.

polesapart · 24 Mar 2020

Gurgling noises on boiler + poor heat transfer to cylinder at high point on sealed system?

I'd be checking that the automatic air vent on the cylinder primary (pic3,post1) is working!

hard-work · 25 Mar 2020

Hugh Jaleak said:
Stick to Google, you are once again out of your depth and it clearly shows. Without being on site you cannot possibly determine the quality of the mains supply. This is a DIY forum and the OP is asking for professional advice. For all we know the OP has a shared Lead supply, which drops to a trickle if demand is made elsewhere, making all your ideas useless and/or pointless. It needs someone to survey the job and offer the best option for the individual circumstances.

There may even be little wrong with the current system that a flush and service wont sort out.

Just re-read what I wrote. I doubt you know what installing a H&C system is, never mind balancing one is. You smell of cowboy.

Gasguru · 25 Mar 2020

A lot of poor advice being given on here by some very biased ignorant posters...

Modern unvented cylinders loose negligible heat and for 6 months of the year that minimal heat contributes to space heating.
The myth of combis being more efficient was promoted by the manufacturers that predominently sold combis.
How efficient do you think a combi is cycling 100s of times a day?

Pressures and flowrates must be measured before any decisions can be made.

hard-work · 25 Mar 2020

Gasguru said:
A lot of poor advice being given on here by some very biased ignorant posters...

Modern unvented cylinders loose negligible heat and for 6 months of the year that minimal heat contributes to space heating.
The myth of combis being more efficient was promoted by the manufacturers that predominently sold combis.
How efficient do you think a combi is cycling 100s of times a day?

For the average British home, unvented cylinders add extra cost and complexity. More to go wrong with also an annual service needed, adding more costs.

What is this 100s of time a day cycling? Modern combis have OpenTherm controls. They just modulate down and then silently purr.

Far too many push outdated technology that gives them more money to install. Or they just haven't a clue what is on the market. Unvented cylinders are for when the hot water needs are large. I had one fitted in a job which was all electric. Heating was electric UFH. They do have their uses, but in the average British home with gas? They are difficult to justify. They suffer the same constraints as combis being mains water systems.

Hugh Jaleak · 25 Mar 2020

hard-work said:
You smell of cowboy.

I only have a City and Guilds 603 Plumbing Craft qualification, and 30 years experience in the field.

As I recall you have never stated your qualifications or experience on any post you've made under any of your pseudonyms, instead preferring to slate experienced and knowledgeable people as 'cowboys'. About time you were banned from this Forum for good.

Gasguru · 25 Mar 2020

Hard-work you really live up to your name, you really do talk garbage....
5 mins with the air compressor after the boiler service....such a big deal.
Complicated? Only for the stupid...a couple of 2 ports, couple of safetys and a PRV.
Cycling...I'm talking about the hot water demand you muppet.
You're forgetting the key advantage....a backup immersion heater.
I don't think you have any idea how often combis pack up and the hot waters lost, and it's often at the most inconvenient times.

Good luck finding anyone to fix your combi at the moment...most of us in the gas trade are 50+ and few of us are risking working at the moment.

hard-work · 25 Mar 2020

I reiterate, unvented cylinders in the average British home is an expensive waste of time that consumes space, when assessing the range of quality combi boilers on the market.

The arrangement of the H&C pipework for a combi and unvented cylinder is the same, as they are mains pressure systems. Be weary of those who have one 15mm cold water mains pipe snaking around the house with the combi, or unvented cylinder, just a tee off it. The performance will be invariably abysmal. These installers give the business a bad name.

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Looking to replace water cylinder which type needed?

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