4 story townhouse - Combi or Std boiler? Advice needed

[JohnD]

but combis break down much more often than regular boilers.

no-one will seriously attempt to deny that.

 

[bengasman]

but combis break down much more often than regular boilers.

no-one will seriously attempt to deny that.

I would, and not only that, you will agree when you think about it.

Reliability of a ch system depends for 90=% on two factors.

The quality of the boiler.
The quality of the installer.

I refuse to do budget installs, and I have had no breakdowns at all in the past 5 years.

What is the breakdown rate of heat-only boilers from like flexibomb, istor, and that sort of crap?

Besides that, if you look at the the reliability of the whole system, I really don't think heat only scores better than a combi, and certainly not when it is open vent.

 

[JohnD]

I assert that a combi will break down much more often than a regular boiler.

This applies if you are comparing a good-quality, well installed regular against a good-quality, well-installed combi

And it also applies if you are comparing a poor-quality, badly installed regular against a poor-quality, badly-installed combi

Do you consider Plate Exchangers to be get blocked often?

And it is much more inconvenient when a combi breaks down, than a regular with a cylinder which also has an immersion.

BTW, Any competent DIYer can easily change a pump or motorised valve on a regular system, but is not supposed to poke around inside a combi.

edited: typos corrected

 

[bengasman]

...Do you consider Plate Exchangers to be get blocked often?...

Not as often as 2-channel timers, pumps, valves and ballcocks together, and never on boilers that I installled.

If you compare quality systems, installed and maintained by the book, neither will have much chance of breaking down.

 

[Ihavenojob]

If the combi is being fitted on the ground floor,the pump in it may struggle to heat the rads on the top floor,so maybe not just the hot water deciding what you fit.

 

[GaytonTonner]

If the combi is being fitted on the ground floor,the pump in it may struggle to heat the rads on the top floor,so maybe not just the hot water deciding what you fit.

A pump on a combi or any other systems will be in exactly the same situation. Being a combi is irrelevant. A combi is a system boiler with a water section. Look inside both. All makers have most parts of the two being the same. Only a 3-way valve, flow switch, plate heat exchanger and some sensors are the extras.

Because of the competition of combis, many wise installers can get the equivalent combi versions cheaper than the same makers system boilers. Some buy the combi and do not connect up the DHW side, or have the DHW section as a backup in case of a cylinder failure.

 

[ChrisR]

Even the biggest combis struggle in a house where the bathrooms are at different levels, because of less than perfect mains supplies, and less than perfect internal plumbing. The lower shower/bath always works better than the one above when boith are on, and the person in the upper one moans.
One space-saving option can be to use an electric shower in one bathroom, and a combi for the other. They only use about 4 litres a minute. Not a great shower, but the flow's low enough to not affect the combi. And they're a backup of course.

Without measuring the mains pressures and flows, you can't begin to make any decisions.
Overall chance of a combi working to your satisfaction, about 5%!

 

[Ihavenojob]

A combi has the pump it was fitted with&thats it.A system with separate pump,valves etc can use a more powerful pump designed for that system.

 

[wetshoes]

To the OP,
It's worth remembering that with a combi, all your eggs are in one basket - if it breaks down you have no hot water & no heating.
If you remain with a standard heating & hot water cylinder system you have the option of using an immersion heater to get hot water .

hth wetshoes

 

[mysteryman]

Combi or System? It's largely down to your own preference. If you are considering an unvented cyl you are still utterly dependant upon your cold main flowrate to deliver everything in terms of water flow.

The only real difference between a combi and a system boiler is that the combi has a domestic water flowswitch and a plate heat exchanger. Neither of these components on their own will make the boiler significantly unreliable. You will need external extra equipment with a system boiler anyway.

A properly installed quality modern boiler should be reliable. See other comments about who provides the best factory back-up. Choose what you want, and find an installer you feel you can trust.

 

[mehran]

why not go for a thermal store

 

[ChrisR]

You are passing off a poorly designed and installed system as the norm.

No. I'm going by experience.
Which you don't have.

This is nonsense.

Ditto. Experience. Something you wouldn't know about.

First, the mains pressure and flow must be capable.
Secondly, the water system MUST be installed properly.

But he's got what he's got, he isn't going to replumb the entire house just to satisfy your perverted opinion.

You don't need as perfect a mains supply if you store water. Surely even you can understand that

fit a cold water accumulator

the problem is space. A silly answer.

I think it's time we got you banned again, you're talking out of the wrong orifice too much.

 

[mickyg]

A pump on a combi or any other systems will be in exactly the same situation. Being a combi is irrelevant.

Well you can tell that to the customer who last week needed a pump changing on his combi boiler. The pump in question was a Wilo, but specific to the appliance. It cost £189 just for the pump at trade price. A similar wilo pump for a standard system can be bought in screwfix for about £40.

 

[GaytonTonner]

You are passing off a poorly designed and installed system as the norm.

No. I'm going by experience.
Which you don't have.

It is clear I am no DIYer. But you come across as a slap it in cowboy.

First, the mains pressure and flow must be capable.
Secondly, the water system MUST be installed properly.

But he's got what he's got, he isn't going to replumb the entire house just to satisfy your perverted opinion.

A good mains pressure and flow is not a perverted opinion. I notice you are from London. A city festooned with cowboys.

You don't need as perfect a mains supply if you store water. Surely even you can understand that

Any system that runs from the cold mains needs a good cold mains supply, even unvented cylinders, as it all comes down the one pipe. That is how mains systems work.

I doubt you have ever seen a cold water accumulator.

 

[GaytonTonner]

A pump on a combi or any other systems will be in exactly the same situation. Being a combi is irrelevant.

Well you can tell that to the customer who last week needed a pump changing on his combi boiler. The pump in question was a Wilo, but specific to the appliance. It cost £189 just for the pump at trade price. A similar wilo pump for a standard system can be bought in screwfix for about £40.

Change just the head of the pump.