Expert advice needed on Valliant combi boiler

[seebo]

Hi All
I am changing my boiler as previous one old and struggled to cope with heating all the rads.
I have had a couple of quotes and decided to go for a valiiant combi however my dilemma is which one should I go for. One of the guys suggested the 43KW the other one says 38KW is suffice as I would be wasting alot of gas on the bigger model. I have 21 rads and currently one shower thinking of installing in second shower to run off combi.

Which would be the best model to go for would i be wasting gas by going for thee bigger one if I choose the 38kw will that be ablle to cope with heating all the rads ?

Valliant ecotec plus combi 838 OR
Valliant exclusive with green IQ 843

I would like to thank everyone in advance for any suggestions and replies.

 

[flameport]

I have 21 rads

Of what size, and more importantly, total heat output?
How big is the house?
What is the existing boiler?

 

[muggles]

What's your incoming mains flow rate & pressure?

 

[heatservice]

The model number denotes the Kw output for hot water so the 838 gives you a maximum of 38 Kw/h to water which in ideal circumstances would gve you almost 16 litres of hot water per minute at your taps/shower, the heating output however is only 28Kw/h maximum not 38Kw/h as you might expect for the 838 model

 

[dilalio]

What's your incoming mains flow rate & pressure?

@seebo This is rule No. 1 when considering a direct mains system, such as a combi or UV.

 

[bernardgreen]

For what it is worth........ Last week a burst water main cut off supplies to some houses in the village. Those families with cold water storage in the loft and vented hot water cylinders had the advantage over those who could not flush their toilets.

It is only when the water supply fails that the advantage of "old fashioned plumbing" become obvious

 

[dilalio]

For what it is worth........ Last week a burst water main cut off supplies to some houses in the village. Those families with cold water storage in the loft and vented hot water cylinders had the advantage over those who could not flush their toilets.

It is only when the water supply fails that the advantage of "old fashioned plumbing" become obvious

“Bernard Green, News at 8:00, and now back to the studio...”

 

[bernardgreen]

“Bernard Green, News at 8:00, and now back to the studio...”

Humour apart at least one "modernist" family who had installed the latest system ( and therefore best ) of plumbing had to eat hunble pie and use their neighbour's toilet supplied from the old fashioned tank in the loft.

To be fair one "modernist" couple were using buckets of water from their rain water butt to flush their toilet. They had their butt high enough off the ground to be able to get the bucket under the tap. Others were not so lucky

 

[picasso]

In the last 30 years I think my water supply has been cut off once, the water company had it back on next day, hardly a reason to keep crappy old tank feed plumbing.

 

[bernardgreen]

hardly a reason to keep crappy old tank feed plumbing.

at least you can flush away the crap and wash hands a few times before the tank runs dry.

It is not a crappy system. It is a system which is not dependent on high pressure and high flow rates in the incoming water main. How often do accumulators have to be installed to try and deal with low flow rates and low dynamic pressure on the incoming main. An accumulator is a cold water storage tank that has to be pressurised.

 

[Razor900]

How often do accumulators have to be installed to try and deal with low flow rates and low dynamic pressure on the incoming main.

Erm not very often Bernie actually....

 

[oldbuffer]

Ever since the local water company stopped using a water tower and installed pumps, I lose water at least 4 times a year, as soon as there is an electrical fault. Time off varies from an hour to overnight. So no unvented hot water, no combi boiler. This is not anywhere rural, its West London.

 

[John D v2.0]

Ever since the local water company stopped using a water tower

its West London

Is that the one that was on grand designs and turned into a couple of million pounds flat on a stick? Great if you don't like neighborsn!

 

[Hot&Cold]

Ever since the local water company stopped using a water tower and installed pumps

Looked at purchasing a top floor flat in a converted thames water tower in oldbuffer's area and the water pressure was pish poor,maybe oldbuffer had his sprinkler out

 

[bernardgreen]

Water Tower in the wrong place ?, then move it........https://media.anglianwater.co.uk/the-moving-of-milton-ernest-water-tower/