ACV / Vitodens 333 or unvented + system boiler?

Dre

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1 bath, 1 shower, 1 wetroom (with body jets) 4 Bed house.

3 bar incoming, 25l/m flow rate. Need best bang for the buck and more importantly good flow for the showers.

recommended ACV 35tc or Vitodens 333, looking at specs the ACV seems superior as it has a larger store and hence greater capacity for showers & body jets (35l/m vs 19l/m). Is this correct? Also can anyone recommend a place where I can obtain the boiler? Can't seem to find a supplier on the net? Maybe one of the large merchants - PTS, although the one I called had no idea of the brand??

Other option was - unistor with eco tec boiler - but not sure what combination of each? Also I don't see the difference, one is in a single unit minus Immersion the other is two separate units (more points of failure? or better resilience?)


All thoughts appreciated. Purchasing by the end of the week so please help.
 
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You won't easily get an ACV except through an installer, they are wary of selling to the general public.

You won't find a price on the internet.

Any dealer that deals with ACV will supply one. Many dealers sell ACV tank-in-tank cylinders.

For the walk in wet room you need volume of water stored as well as flowrate delivered. The ACV will do this but will drop in flowrate as the unit becomes exhausted. It may not cope with the wet room body jets.

You have 25 litre/min, and that is hot and cold, so any appliance flowrate above this is overkill. An ACV may actually run out hot water if someone is in the wet room body jets for a while. You need either:

1) A large large storage vessel (which takes lots of space, and expensive)
2) Instant hot water high flowrate combi, which takes little space, and never runs out of DHW


Instantly heated water is the way with your demands.

A cheaper solution than the ACV is the high flow Ethos 54C combi that delivers around 24 litres./min.
http://www.ethosboilers.co.uk/products_54c.php

Or the best and most cost effective solution is two Broag 28C combi boilers,
  • combined will give 23 litres/min - just right for you.
  • Have one do the kitchen DHW,
  • Have one do the utility DHW,
  • one do the shower DHW,
  • combine both DHW outlets using two check valves and shock arrestor for the bath and wet room body jets.
  • you have backup.
  • Have one do downstairs CH (CH zone 1) - no headers needed.
  • Have one do upstairs CH (CH zone 2) - no headers needed.
  • You will always have DHW somewhere in the house if a failure.
  • You will always have CH somewhere in the house if a failure.
  • The Broags have integral outside weather compensation (great comfort conditions and great low temperature economy)
  • The Broags have a superior control system (OpenTherm standard) to W-B & Vaillant
The Broag are better quality than Vaillant and much cheaper. They are a well priced quality boilers having a superb control system, superior to W-B and Vaillant. http://www.avantaplus.co.uk

Two 28C Broags are just under £1,300. That is with the integral weather compensation, which lowers and raises the radiator temperatures to the outside temp and saves gas. W-B and Vaillant do not have this as standard, and W-B not at all. An ACV is circa £2,800 the last time I looked (great kit though)
http://www.tradingdepot.co.uk/DEF/c.../Central Heating Boilers/Broag Remeha Boilers

The control options. Wiring the combis is simple:
http://www.avantaplus.com/docs/Issue 5 -Avanta Schematics Booklet.pdf

Using two 28C combis is by far the most cost effective solution by a country mile, delivers the DHW you need, never runs out of DHW and gives zoned outside weather compensated CH (cheaper to run).
 
Any dealer that deals with ACV will supply one. Many dealers sell ACV tank-in-tank cylinders.

Cheer bb...any thoughts on the other questions in my post? Just looking for confirmation I'm going down the right route rather than an expensive mistake.
 
Any dealer that deals with ACV will supply one. Many dealers sell ACV tank-in-tank cylinders.

Cheer bb...any thoughts on the other questions in my post? Just looking for confirmation I'm going down the right route rather than an expensive mistake.

Basically I have covered all your points. You need flowrate that lasts. You may be disappointed in the wet room if the hot water runs out, and many are stung when fitting these body jets into houses and do not uprate the DHW capacity, having 5 minute showers. Then they have a big bill of £1,000s to uprate the cylinder to very larger one.

Instant DHW gives what you need. Stored water just cannot deliver what instant DHW delivers. If you are 30 minutes in the wet room at 20 litres of hot water delivered, that is 600 litres in 30 minutes. That is a massive very expensive unvented cylinder, taking up lots of valuable space. The recovery rate for a 600 litre cylinder is around an hour with a reasonably powerful boiler.

The two Broag combis will also give zoned CH. It divides and rules - two simple combis, taking little space - they can even be in different parts of the house to hide them. The solution offers so much, than others to meet your needs. Running costs are now important as energy prices rise. And... the two combi route is by far the cheaper option to guarantee confident operation and delivered service to you the customer. The only down side is that you have two boiler services per ann. Note: if you went with an unvented cylinder they require a service too, so no different in that respect.
 
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Thanks BB very informative. Can the Broags be mounted one above the other? I basically have enough space for whatever system I can get in a cupboard thats 600Wx600Lx2400H
 
Thanks BB very informative. Can the Broags be mounted one above the other? I basically have enough space for whatever system I can get in a cupboard thats 600Wx600Lx2400H

They can be mounted over each other. The instructions (downloadable on-line) gives the minimum distance between flues.

As I said, it is matter of dividing and ruling. Having two separate combi systems in the house, one doing up and one doing down, and combining the DHW outlets when needed for high instant flow rates at wet room and bath.

It is then easy for the local service man to fix being all domestic and separated - he doesn't have to think, which is problem with many of them. Even if in 10 years time a combi needs replacing it is still a simple cheap swap out job, taking a day at very most. The Broags should last circa 20 years.

BTW, fit a Magnaclean filter on each boiler on the return from the rads. That will make sure the boilers last.
 
Dre, a posting you made has disapeared for no good reason!

In it you said that your plumber does not speak English but was CORGI registered.

Part of the registration process is to take many technical assessments. Its difficult to imagine how anyone could achieve that if they did not speak and read English very well !

Are you quite sure he really is registered and do you know his CORGI number?

Tony
 
Gasvinda, did you wonder about the posting disapearing or about how anyone could get CORGI without speaking English?
 
I'm wondering about both now that you have pointed it out...what I said was he didn't speak great english, not that he didn't speak english.

Not sure why the post got amended.
Any thoughts on the above recomendations? Would you guys suggest another approach? I was totally convinced on the storage boiler - however got a quote on the ACV £3K + vat!! so the two combi option is looking good if not the vitodens.
 
however got a quote on the ACV £3K + vat!! so the two combi option is looking good if not the vitodens.

The Vitodens 333 may run out of DHW too - it is a stored water combi. I think it reverts to what the burner can supply after the stored hot water is exhausted. Remember you have a wet room with body jets and the burner of the Vitodens will only give around 10 litres/min, once the store is exhausted.

Don't dismiss the outside weather compensation that the Broags provide.

NOTE: You may require a pressure equaliser before the body jets and shower mixer. Have a dedicated cold inlet 22mm pipe from the stoptap to the combis. Tee off at the stoptap and take the cold from that pipe. Just before the combis, tee of the cold fee and take the cold supply to the body jets and shower mixer - the only cold tees off this line.
 
[quote="BigBurner";p="1079391
Don't dismiss the outside weather compensation that the Broags provide.[/quote]

I thought that was only for the heating? Also looking back wouldn't the Ethos do the job in just one unit? I know I won't have the redundancy but I would save on space and cost?
 
Don't dismiss the outside weather compensation that the Broags provide.

I thought that was only for the heating? Also looking back wouldn't the Ethos do the job in just one unit? I know I won't have the redundancy but I would save on space and cost?

Weather compensation is only for heating, but gives great economy and comfort. The Ethos will give you the flowrate and is an excellent boiler. But the cost is slightly more than two Broag combis. Price it. Last time I looked it was around £1,400. It does have weather compensation too. It also has a secondary circulation loop kit giving instant hot water at the taps, although you can rig one of these up yourself, maybe cheaper.

Two combis gives you CH zoning. If space is a problem then the Ethos looks good.

As above, have a dedicated 22mm cold feed to it.
 
Dre

Be wary of BB advice, he is only advising from searching the internet and reading manufacturers info, something that you are well capable of doing yourself.

He has never seen one of the boilers he promotes (other than at a trade stand), let alone ever fitted one, or know how to :rolleyes:
 
A Corgi fitter with poor English is probably a lot better than an internet jockey who has never fitted a boiler but has an obsession with Broag.



As an aside, it seems that if I give a link to pictures of an ACV installation, I am advertising, even the the OP has already stated that he is going to buy one directly himself and I have clearly stated I wouldn't entertain fitting one on this basis.

If I can't refer to actual fitting pictures, how come others can post their installations directly on here?

I think there is a bit of a dual standard being applied. Can the moderator concerned confirm he/she is not a heating installer/maintainer?
 

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