Worcester greenstar 30 kw cdin syetem boiler install

[richardd]

I am replaceing a baxi sytems boiler with the above. There is a heating pump and and expansion vessel already fitted from the baxi.

Should I take the pump out and the expansion vessel as the grenstar has theses features within the boiler . Or will the system work fine without having taking them out

 

[Bartdude]

Are you the installer or an interested customer?

 

[richardd]

Installer althougth pretty new to the work . Just out of my time spent most of my time on industrial work. Having moved into the domestic market and just acheived my gas safe course.

I think the syetem will be fine without taking the pump and vessel out.

 

[Bartdude]

You said you are replacing a Baxi system boiler. A system boiler has expansion vessel and pump built in,so it should be a straight swap,as long as the expansion vessel matches the system volume.

If the boiler is a heat only model and the pump an EV are separate,then you would remove them when you fit a system boiler.That's pretty basic stuff really,have a good read of the installation instructions.

 

[richardd]

The baxi must be a heat only model as there is a pipeline pump beside the boiler and a vessel in the loft area .

 

[bengasman]

If the boiler has a pump in it, take the old one out.
Leave the external ev, it won't hurt.
30kW? Must be a big house, are you sure you need a boiler that big?
Which fga do you use for this?

 

[richardd]

its 6 bedroom 3 bathroom. fga ( whats that ) flu gas analyzer

 

[bengasman]

fga ( whats that ) flu gas analyzer

Yep, analyser.
By the way, make sure you use an independent timer that allows you to set ch and dhw times to be never on simultaneously; it can make a huge difference.

 

[richardd]

There is a an s plan honeywell smartfit control system fitted already from the baxi I was goint to connect to this. Althought disconnecting the pipeline pump from the baxi will that work fine.

 

[richardd]

What difference does it make.

 

[bengasman]

What difference does it make.

?????

 

[richardd]

You can do this with the honeywell s plan smartfit.

 

[richardd]

The original 13 year old baxi ( heat only ) was a 30 kw. So with more efficent boiler I may go for a 24 kw heat only ( regular ) boiler. Which will mean i can use the existing pump expansion vessel and honeywell controls. What you think bengasman

 

[bengasman]

I see, never used a smartfit myself.

 

[richardd]

You seem knowledgeable do you think this is a better idea to change the boiler to a heat only like the boiler and system before and go down to 24 kw. Rather than the systems boiler.

 

[bengasman]

The original 13 year old baxi ( heat only ) was a 30 kw. So with more efficent boiler I may go for a 24 kw heat only ( regular ) boiler. Which will mean i can use the existing pump expansion vessel and honeywell controls. What you think bengasman

I use a different approach than most.
I don't do heatloss calculations on existing systems because my clients tend keep their radiators as long as they warm the rooms up sufficiently. They don't want to spend money to satisfy a theoretical calculation, nor would I recommend they did.
Therefore, I simply measure the total length of radiator panels present, adjust that to 600 mm high, and then take one kW for every meter length. If there are no consideration for extensions, that is the number of kW boiler I go for; next boiler up from that number is what I get.

Forgot to ask, apart from model fga, how did you come to that choice? I am writing a couple of articles on fga use, and am trying to find out some different views about them.

 

[Bartdude]

You need to do a heat calculation to know what size of boiler is required for the house,24 kw may be ok,or it might be undersized,hard to say without seeing the house.

 

[richardd]

anton sprint kit 2

 

[bengasman]

You need to do a heat calculation to know what size of boiler is required for the house....

What would you do if the heatloss calculation indicated 40 kW, but only 20 kW worth of radiators installed ( or vice versa ), and the client finds all the rooms warm enough?

 

[bengasman]

anton sprint kit 2

What made you choose that one?

 

[richardd]

used it in trainig course . instuctor recommended it . You can also get 8 calculations on one screen

 

[richardd]

So if there is a total of 22 meters of lenght in all the rads you go for a 24 kw boiler. Is this what you mean

 

[bengasman]

That's it.
The calculation may say 30, 40 or whatever, but if the rads can't dissipate it, there is not much point in getting a bigger boiler if the client has no intention of adding more capacity.

 

[bengasman]

used it in trainig course . instuctor recommended it . You can also get 8 calculations on one screen

Thanks.
Being relatively new to this, what do find the number 1 advantage of using fga, and what the biggest downside ( don't say costs )

 

[richardd]

Accurate calculation and piece of mind . Its also a must theres no getting round it if you are a professional engineer