Worcester Highflow 440

Can you range rate these? As they incorporate forced draught combustion -is there any need to? (is this a stupid question)

I ask as we are fitting one in work and read the manual back to front and no mention of a gas adjustment for CH system size.

It modulates automatically, from 7.4 to 30+ Kw in CH mode. Why / how would you set about range-rating it?

It is a stupid question because the need to range rate the boiler does not arise from the combustion method.

I think the range rating is within the "Service Functions" briefly shown on page 34.

The problem is that because so few installers properly commission the appliances the manufacturers try to find ways to reduce the need to make these settings.

I think its Worcester who will provide a free commission. This is because getting it properly installed and set up will reduce calls under the warrantee.

One way many of the latest designs get over the lack of range rating is through the "soft start". They start up on minimum power for about 5 minutes and then ramp up if the return temperature has not started to increase.

I will try to get the Service Functions info out of Worcester. Woe betide them if they refuse!

Any of the Worcester staff engineers care to comment?

Tony

So am i right in saying that you do not have to R-rate a combi that modulates the CH and DHW, though most combis only modulate the DHW?
If a boiler modulates the CH it will work effectivly for any size CH system (between the boilers modulating range) without modification?



Cheers for the replys.

"though most combis only modulate the DHW? "

Depends a bit what you call modulation. Many only go hi-lo, ie on-off on a mod coil on the gv. Some "step". Depends how sophisticated they are.
Modern ones all (?) modulate on CH, but some tend to run in to overheat if the CH is set to max output and they only have a tiny flat with 4 rads. (Ideal Minis ... )
You'll notice some 28kW combis are factory set at lower output on CH, say 18kW.
So in theory they should cope, but its still a good idea to get it roughly right. The boiler has to run to "see" what its load is like. If it does that from flat out every time it comes on it'll be wrong most of the time.

Manufacturers tech helplines are unreliable on this. Some of the individuals don't know much. I was told very definitely that early Turbomaxes don't continuously mod on hw. But if you turn a tap on low and watch the burner pressure, down it goes, smoothly.

"Service Functions" briefly shown on page 34.

Click to expand...

Page 30 in my version of the manual! Points up another problem: no proper edition control of the MI so you never know whether the manual you've got actually relates to the boiler you're trying to fix! I can't point to even ONE manufacturer who does this right.

IF the electronics / software in the 440 is the same / similar to other WB current models, then there is no 'master' output adjustment via the service functions (according to WB, when I REALLY needed to throttle-down a boiler).

Bster, you keep coming out with incorrect statements. Each boiler is an individual design and no general statement will apply to all models.

Virtually ALL current boilers DO modulate in both CH and DHW.

If its possible the CH output should be set to match the requirements of the heating system. ( as you were taught on your energy efficiency )

The problem is that although most boilers have the ability to set the CH output, a very few dont and some others have the facility but dont include it in their MI.

Tony

Right i'm understanding it (a bit) better now, i was just getting confused about all this range rating thing on com . I'll stop stressing now and get back to some simpler problems\queries.... (do Danfoss TP5's use an anticipator?)

I think i'm running before i can walk!! but its good to start learning a bit about these sort of things.

cheers again.