Halstead Boilers

[Dave Plowman (News)]

Try reading the whole post. There aren't any large words in it so you should manage.

[Doctor Drivel]

Please eff off as you are a plantpot.

[dennis]

A 30 kW combi will heat about 4 liters a minute by 30C, so I guess you will get about 4 liters a minute at bath temp.

Pressure and flow aren't quite the same.

[geoff]

In message , Doctor Drivel writes

err .. no

did they stop your med again or what ?

[Doctor Drivel]

Maxie!! You did!!! I do like the way you josh. Fantastic indeed. Such a one you are! Such a one! A hard drinking, hard swearing, motor bike riding, frock wearing man. Fantastic indeed. Fantastic! And Maxie knows things too.

[Doctor Drivel]

It is? It must be broke then. A quick look at makers specs will tell you that on a 35C temp rise it will give around 13 litres per minute.

[Ed Sirett]

I have long since given up arguing with one or two posters since numerical arguments don't cut it and I don't have the skills to come up with better arguments.

However without any calcs I'm certain a 30kW instant water heater (or combi) can provide over 10 litres/minute @ 30C "delta-T"

By calculation let's say that the 30kW boiler does 26kW or actual water heating (85% efficiency).

So mass flow rate (kg/s) is 26,000 / (30 x 4180) = 0.207 so Litres/minute is 0.207 * 60 = 12.4 kg/minute The kg/minute is very slightly lower than the litre/min. Say 12.5 litres/ minute

[dennis]

Well I must admit that I was doing mental arithmetic but..

30kw is 30,000 joules per second divide by 4.2 for the specific heat of water >7140 grams by 1 degree rise per second. x 60 /1000 to kg(l)/min

gives about 12 so yes I cocked it up somewhere, not by enough to actually make much difference, even a 30kw combi is *slow*

[Dave Plowman (News)]

In defence of them, a decent one is only slow to fill a bath. For all other things including showers they should be ok.

FWIW, even an instant electric shower manages more than 4 lpm.

[Doctor Drivel]

Slow for what? I find a 28kW combi fills a bath fast enough. Turn on, prepare, get undressed, get in and still leave running when in the bath. No probs.

The Glow-Worm Ultracom 30 CX combi gives 12.3 litres per min at 35C temp rise. A 40Kw combi: few peoepl complain of the performance.

[Dave Plowman (News)]

But you find lots of things acceptable no human would.

Only those who use baths a lot.

The fact is no combi can match a decent storage system for flow rate - no matter how you squirm and dribble.

[Doctor Drivel]

A decent one fills a bath no problem at all.

[dennis]

You are just easy to satisfy. My system is able to put ~30kW into the hot water tank that is already at

60C, if I wanted to I could run three or four baths in the time a combi would run one. Insulate the boiler feeds and the tank well and it will waste less energy than the combi uses keeping its little store hot.

I am always amazed that nobody insulates the boiler feed and return, it keeps the heat down in summer.

[Doctor Drivel]

You must eff off as you haven't a clue and are a total plantpot.

[dennis]

Lets see.. how long does it take to get undressed?.. about 30 seconds.. How deep will the water be after 30 seconds?.. about 10 mm if its a small bath. Do I not see a problem here?

I have noticed that baths are smaller these days, I wonder why?

[Doctor Drivel]

No. I just know a hell fo lot more than you.

Not unless you have a 600 litre hot water cylinder. You must stop guessing. At 12.5 litres/min a combi can deliver 750 litres an hour. That is about 6 or 7 average baths. They can fill bath after bath and don't need recovery.

That is why many catering kitchens have instant water heaters as to deliver the water they need they would require a cylinder of 1000 litres or so, taking up lots of space and costing a fortune to install. A cheapish instant water heater does all of what they need - and some instant water heaters can be fitted outside too.

[Doctor Drivel]

Yes. In 30 secs filling from a cylinder would be about the same.

To save water and energy.

>

[Dave Plowman (News)]

What industrial premises need or do has little bearing on domestic requirements.

[Doctor Drivel]

Please eff off as you are a total idiotic plantpot.