Recommend a 24kw Combi

[fixitflav]

Bernard, the days of baths are receding. Many new homes have walk-in showers, many with double shower trays with no doors. Many rip out baths and fit walk-in showers as I did. Older people prefer walk-in showers rather than slipping in baths causing injury. A 90 year old neighbour just slipped in his bath - not nice. In walk-in showers they can just put a plastic chair in there if they need to sit. A high flow combi does these showers very well.

Gledhill listened to architects and came out with the thermal stores that do not need discharge pipes or overflows and no chance of explosions. This meant the store can go anywhere in a home not just on an outside wall. This gave architects greater scope for internal design of a home. A combi gives that flexibility as well.

How did pressurised HW cylinders and thermal stores get into it? They may have advantages (and disadvantages) compared with conventional cylinders, but not in terms of space requirements or location options, as far as I can see. I've never seen it done, but in principle a conventional HW cylinder could go in the attic, if levels were taken care of, and perhaps primary pressurised with expansion vessel, to avoid elevating the F/E tank.

 

[hard-work]

Sarcasm doesn't help the discussion. I didn't say all combis are useless, I just gave an example of something going wrong. I've never heard of it happening with a HW cylinder.
How about my first paragraph?

You were clearly putting it across because a combi can break down, like all boilers, they are not worth looking at. A cylinder zone valve can pack up, a boiler providing the heat to the cylinder can pack up, a cylinder thermostat can pack up. A friend of mine has had an ATAG combi for 9 years and it has run like a Swiss watch in all that time.

 

[hard-work]

How did pressurised HW cylinders and thermal stores get into it? They may have advantages (and disadvantages) compared with conventional cylinders, but not in terms of space requirements or location options, as far as I can see. I've never seen it done, but in principle a conventional HW cylinder could go in the attic, if levels were taken care of, and perhaps primary pressurised with expansion vessel, to avoid elevating the F/E tank.

Please focus. Clearly in flexibility of interior space design is there with a combi, as there is no bulky cylinder. Back to my original point: in the average British home, as long as the cold water supply is fine, a combi will meet the needs. The advantages of a combi over a boiler/cylinder setup is vast.

 

[bernardgreen]

a boiler providing the heat to the cylinder can pack up

and then the immersion heater ( if fitted ) can be used to provide hot water.

The advantages of a combi over a boiler/cylinder setup is vast.

maybe true in the installation process for the installer but the low efficiency when supplying DHW means gas consumption is higher and the cost of wasted water is significant, as nuch as 10% goes to waste before the boiler is producing hot water.

I do wonder if hard work was duped by a get rich quick "heating engineer" into having a combi installed and is now too proud to admit that it was a mistake. He wouldn't be the first to make this mistake. Dented pride can result in sarcastic comments when trying to defend the mistake.

 

[hard-work]

maybe true in the installation process for the installer but the low efficiency when supplying DHW means gas consumption is higher and the cost of wasted water is significant, as nuch as 10% goes to waste before the boiler is producing hot water.

Bernard, I gave you a link to the ATAGs with flue heat recovery - highly efficient. More efficient than a cylinder with its standing heat losses. And space the unneeded contraptions take up? I even told you how to pipe them up properly. The DHW flowrate of combis can match that of cylinders for the average home for sure. Bernard you are regurgitating myths of 25 years ago.

All you have to do is look at the specs of combis. Not difficult.

 

[hard-work]

Bernand my combi is brilliant. Look at the pictures of the bathroom. In one you see a ceiling mounted mini-drencher shower head. The business.

 

[JohnD]

More efficient than a cylinder with its standing heat losses.

Is that actually true? In summer, every time you turn a hot tap on, you are heating up a mass of metal and water just to let it cool down again.

 

[hard-work]

In winter you are not heating up a mass of metal. Every time you turn on a tap in summer you are not heating up a mass of metal. The heat exchangers stay warm for while. Cylinders are not insulated under the cylinder. There is heat loss via the hot draw off pipe as well - in fact via any pipe connected to it. They have high standing losses. Look at the ATAGs I gave the link to. Integrated flue heat recovery. Your Luddite tendencies are still here.

 

[bernardgreen]

The DHW flowrate of combis can match that of cylinders for the average home for sure. Bernard you are regurgitating myths of 25 years ago.

The data posted on an architecural forum is current, not 25 years old. Measured efficiency values ( derived from gas volume, water volume and rise in temperatures ) for combi boilers in average UK homes have been as low as 30%. Add to that the cost of the cold water that flows out of the boiler before the water starts to heat up and the financial efficiency of a combi boiler is significantly lower than the financial efficiency of a system with a hot water cylinder.

 

[JohnD]

In summer

perhaps you missed that bit.

high standing losses

What do you think my gas usage is, in summer, with a cylinder supplying baths and showers?

 

[hard-work]

the financial efficiency of a system with a hot water cylinder.

Total and utter nonsense.

 

[hard-work]

What world are you two in? With a cylinder you have to heat the whole thing up just to get hot water out of it to wash a cup. And that will take an eternity.

 

[Dan Robinson]

And that will take an eternity.

Define eternity.

 

[hard-work]

Define eternity.

Doddy, far longer than needing hot water to wash a cup. How are things on the combi growing plantation?

 

[Dan Robinson]

Interested to know what percentage of my boiler installations a year are actually combination boilers (functioning as combination boilers)? .