Question on hot water from combi

[Tim Watts]

On Wed, 20 Jan 2010 18:31:51 +0000, John Rumm wibbled:

Are there tables to convert angle of dangle to celcius?

[John Rumm]

Indeed, correctly.

Catchup at the back, I just said that.

For an 84kW boiler? Interesting concept...

Yup, my thoughts exactly last time you concocted a similar scheme...

For the avoidance of doubt, "no one" includes me. Some combis are very much better than others in the flow rate department. However exotic combis are not what the majority of folks buy or have fitted.

You are indeed as always. Night night dribble.

[The Natural Philosopher]

John, WTF is Drivel doing out of your killfile. Surely you have learnt not to engage by now?

[John Rumm]

I tried adding him to the kill file once... but the hitman refused to go to the nursing home in milton keyens to carry out the job, and so he is still alive.

[Doctor Drivel]

...and wrong.

You never.

It is. Pity you don't need one in normal domestic house.

"exotic combis", he makes all this up.

[Doctor Drivel]

Yep, each time the Chav does he gets a hiding.

[Doctor Drivel]

Sounds like a Chav from Essex. He even got the town wrong. How is the American Bull Terrier?

[ARWadsworth]

John

The simple answer is to fit two combis.

Then there will be no problems at all.

Adam

[Doctor Drivel]

Yep. Two combis can deliver near 64 kW of DHW at a combined flow rate of around 28-29 litres/min. The cost will be around £1600. That is in one hour 1,740 litres of DHW delivered. Fantastic!! How much would 1.500 litre unvnetd cyldiner cost? And the building to house it? Amazing!

[John Rumm]

A 32 kW combi will not deliver 14.5lpm in the winter - more like 11 lpm. So two of them will manage 22 at best. That assumes you have no other gas appliances as well or your would have to use smaller combis.

The cost of having a pair of 32kw combis fitted will not be £1600 either.

I thought you claimed to understand this stuff dribble? Your grasp really does seem poor. 1300L if you are lucky, and at final temperature.

64kW for a hour, is 230.4MJ. 500L unvented cylinder at 70C can store 136MJ (assuming a lift over 5C inlet temp), plus 115MJ from a single 32kW boiler amounts to 251MJ for a modest boiler and an comparable price cylinder. Not only that, you can have an immersion backup on the cylinder and have additional gas appliances without any worries.

[Doctor Drivel]

You just don't know, being a Chav. With a mains water pipe too near the surface giving 5C, not 10C, it will do around 13 l/min, that 26 litres/min. That beats most unvented cylinders.

Two 32kW combis can be used.

Min 1560 litres perhour.

What tripe you are making things up again and squirming. This is what happens when you come from Essex. 64kW is in question, and what it can deliver per hour. Have you seen the size of a 1,500 unvented cylinder? I doubt it. Have you seen the price? Commercial jobbie.

[John Rumm]

Sorry to have to bring reality into this, but, do the sums old chap and stop guessing.

32kw out, inlet temp 5C, exit temp 45C, so 40C lift. 32000*60/4200/40 = 11.4 lpm

Secondly, you conveniently seem to forget that an unvented cylinder will store water at significantly more than final temperature - so even if you claim the cylinder imposes a higher flow restriction that the combis plate HE, then does not have a bearing on the flow at the point of use since you will be mixing cold with it at the same time.

With no other gas appliances.

If you buy crap combis and DIY. Not an option available to most. Most

Or not as the actual figures demonstrate?

Indeed, and we have already demonstrated what 64kW gives you in an hour.

Which clown introduced the 1500L cylinder in the first place? Oh hang on I remember... how is that red nose of yours today?

We have already shown that a 500L cylinder and one 32kW boiler will out perform it in delivery for an hour.