Electric combi tankless boiler?

[rhlee]

Hi all,

My 15 year old gas boiler is on it's last legs. It is in a flat located several meters from any external wall. So due to new gas regs, if I put in a new gas boiler either it would have to be located in the living room or one of the bedroom or have a huge flue pipe running across the apartment. Neither options are ideal. Also the storage tank gives off loads of heat.

For the flue problem, I'm thinking of going electric, like the Amptec or Aztec range of heaters. Ideally, I would like to go tankless as well. Does such a solution exist? So far I can't find any. All electric h/w+heating seem to use storage tanks.

What I was thinking was using dual electric boilers, one for the heating circuit one for the hot water. They seem to do this with the US brand electric water heaters like Seico and e tankless.

What do you guys think?
Have you had any experience?

Rich

 

[simond]

An instant gas combi will use around 24Kw of energy to give a just usable amount of hot water at around 8 litres per min.

24Kw in electric terms means a supply of 100A just for the water heating, if no storage is used.

Clearly this is impractical, especially in a flat.

There are solutions available for modern boilers where flues run internally. Your local gas installer should be able to advise.

 

[rhlee]

Cheers for the reply simon v. helpful.

Initially the plumber said that that the flue would require an incline as well as being quite big. The nearest external wall is 5m away requiring a 1-2 ft drop. And this is going through a bedroom or living room. The other option would be mouting the poiler in one of those two rooms.

However after you mentioned flues, I did a bit more googling and came across the diynot wiki on flues and came across fanned flues. I'm not sure if I understood the wiki entry here //www.diynot.com/wiki/plumbing:flues. But can fanned flues run straight horizontal? How big are the pipes? What about fanned twin flue? What's a good boiler for fanned flues?

Thanks again,

Richard

 

[swbjackson]

The flue must slope back towards the boiler yo allow the condense to run back.

Worcester are supposed to be launching a flue lining system to enable a condensing appliance to re-use an existing flue. This may be an option for you.

 

[simond]

I'm assuming your boiler uses a shared flue such as a SE Duct, or a vertical flue liner in a chimney.

There are solutions available for the latter. There are also ways on converting a SE Duct but this will not be feasible if the building freeholder did not make the arrangements.

Condensing flues will require a sloping flue, around 40mm per metre is typical. But what is the method employed at the moment?

 

[rhlee]

Cheers 4 replying,

swbjackson, is this the worcester flue lining system you are talking about?

Greenstar Si, i and Ri wall-mounted series

New features for autumn 2008 include the ability to pre-plumb the condensate pipework to the wall mounting jig, a universal fitting for the condensate trap, which is capable of accommodating various different pipe manufacturers’ products meaning no additional work has to be carried out on site.

I found it here http://www.worcester-bosch.co.uk/homeowner/our-company/news/greenstar-boilers-make-installation-easy

I checked the installation literature for the i-series, but they still require a 3 degree incline on the flue.


simond, you got the situation I'm in exactly right. The current boiler uses a shared flue. How would I tell is I have a SE duct of a vertical flue liner?

Also my current situation is that the boiler is right next to the shared chimney. The only external walls are the lounge and the bedroom. I don't really want to put the boiler in either. However the external walls are at least 5 m away, so that means a difference in height of at least 20cm. This would be really visible as the boiler is in the cupboard and hence there would be a pipe hanging 20cm down in the hallway when you walk in. (the ceilings are quite low)

 

[swbjackson]

There's no details of the new flue system on the website yet but it's being advertised in the gas installer mag.

 

[rhlee]

Thanks for all the reply guys, especially simond and swbjackson.

I think I question regarding electric tankless combis has now been asnwered, which was it was not really feasible due to the power requirements for such a system would be too high.

As my queries have moved onto condensing boilers and shared flues, I'm going to start a new thread regarding this.

Again thanks for all the help,

Rich