worcester 28 cdi

[trevoratbeer]

Hi

I am retired Electrician (and subsequently poorer) I am looking at ways to reduce my gas bill at home. I have a sealed primary system using a Worcester 28CDi. So I phoned the technical help @ Worcester to ask the following question.

" Given that the cold water feed has an incoming temperature lower than 10 degrees C, and that the boiler has to raise that water from, say, 10 to 45 C for a bath, couldn't I decrease the gas used by heating the cold water feed, before it gets to the heat exchanger ?"

I went on to say that I planned to run the C.W.F through an insulated, indirect copper hot water tank which I would heat via an external Solar Panel. This would save money, even if it only raised the incoming temp by, say 10 degrees.

So, what I wanted to know is, what is the maximum temp that the 28CDi can receive? Logically there must be an upper limit, but for whatever reason I the only answer I got was a flat "You can't pre heat the incoming feed" .

I am not wishing to complain about the level of advice received, rather I would like to understand why? There must be an upper limit, mustn't there?

Any help that you could give, would be most gratefully received.

MYBH

Trevoratbeer

 

[ecowarm]

Hi Trevor

"google grant combisol" it is what you need.
You have an unvented cylinder installed and solar to heat it, the combisol then controls the temp of the hot water to the taps, if it not hot enough to go straight to the tap it mixes the water down to 24C and sends it through the combi.
Most combis can accept pre heated water upto 24c.
I have fitted these and are very good.

Eco

 

[prs1]

Not too good from a legionella point of view if i understand rightly and you are taking about increasing the temp of your incoming mains cold water,even though the water company can get away with supplying it higher its generally accepted that it needs to be below 20 degrees to stop the formation of bacteria in the water.
On a solar set up the panel pre heats the cylinder through an additional coil therefore the boiler doesnt work as hard. ie; 25-60 plus degrees instead of 10 - 60 plus degrees!
Usually done with a heat only or system boiler!

 

[Mbear]

Not too good from a legionella point of view if i understand rightly and you are taking about increasing the temp of your incoming mains cold water,even though the water company can get away with supplying it higher its generally accepted that it needs to be below 20 degrees to stop the formation of bacteria in the water.
On a solar set up the panel pre heats the cylinder through an additional coil therefore the boiler doesnt work as hard. ie; 25-60 plus degrees instead of 10 - 60 plus degrees!
Usually done with a heat only or system boiler!

This is the main issue, don't start messin around with ur incoming mains pal.

 

[trevoratbeer]

Not too good from a legionella point of view if i understand rightly and you are taking about increasing the temp of your incoming mains cold water,even though the water company can get away with supplying it higher its generally accepted that it needs to be below 20 degrees to stop the formation of bacteria in the water.
On a solar set up the panel pre heats the cylinder through an additional coil therefore the boiler doesnt work as hard. ie; 25-60 plus degrees instead of 10 - 60 plus degrees!
Usually done with a heat only or system boiler!

Hmm, thanks. Hadn't thought about Legionella! Still might work, though. IF I only use the combi for my CH. Sealed system so shouldn't be fussed about Legionella, should it? The other part of the plan was to install another HWT in the roof above the shower room (to be made) and heat that above 60C by a PV solar syatem. All this will be thought about a lot before starting next year.

But many thanks for your reply.

Trouble is "When you don't know, you don't know what to ask"

Thanks again.

MYBH

Trevor

Hi Trevor

"google grant combisol" it is what you need.
You have an unvented cylinder installed and solar to heat it, the combisol then controls the temp of the hot water to the taps, if it not hot enough to go straight to the tap it mixes the water down to 24C and sends it through the combi.
Most combis can accept pre heated water upto 24c.
I have fitted these and are very good.

Eco

Hy Eco,

Thank you for replying, i'm learning a lot. I will look into your idea and let you all know what I will decide to do as I do it.

Kind regards

MYBH

Trevor

 

[ecowarm]

The solar PV route is the wrong way to go to heat water!

Solar thermal and heat the water to over 60c once a week to avoid Legionella

 

[trevoratbeer]

The solar PV route is the wrong way to go to heat water!

Solar thermal and heat the water to over 60c once a week to avoid Legionella

Thanks.
It is really good to hear from you guys.
Kind regards
MYBH
Trev

 

[oldplumber]

if you are going to install a cylinder, you could always run the central heating as a primary into the cylinder to act as the second form of heating the cyl hot water and use the cyl water for bathroom etc and just use the combi hot water for the kitchen sink. just requires a bit of lateral thinking and use of zone valves, or go downthe combisol route. Id prefer setting up a proper solar setup than the combisol myself, have fun saving money what ever route you choose