Hot water

[Doctor Drivel]

Yep I recall that 3-way valve kit that fits to the big gap to the left of the heat X. The Avantaplus is all geared up for it, as is the Keston. OpenTherm has taken off in Europe, but UK makers shun it - they want to sell propriety products. It is just a protocol and plug and play using any makers kits as long as it conforms to OpenTherm. An OpenTherm room sensor/timer will modulate the burner. Just pick the most suitable maker.

should be complete by the end of the year. Expect Baxi quality to rise in the next 12-18 months. I would expect the Avantaplus to be re-baged Baxi and some of the crap Baxi-Pott models disappear

The Avantaplus and Keston can use any diverter from any maker and any cyl stat, you are not tied to the maker, so cheaper products. They also have an alternative cyl' sensor to modulate the burner. In a directly heat bank not that beneficial. In a cylinder with a coil smaller than the boiler output the sensor modulates the burner instead of cycling. And it modulates when reaching full temp when the the coil is big enough.

I am underwhelmed by Vaillant and W-B. the Remeha is better in quality than both yet far cheaper for what you get. The 39C combi @ 15 litres/min is just under £1K with weather compensation thrown in. Price up a Glow Worm, Vaillant, W-B to do the same and the price of them is off-putting. They use established quality components. The Heat X is SS. The range is comprehensive with system, open vent and combis. It is similar quality and reliability to Atmos, which are about the most reliable along with ATAG. The Dutch boiler are best at the mo'.

The Remeha web site has a file that gives many setups and the wiring to suit.

[Doctor Drivel]

Please connect everything up using rubber hose and hose clips. Please do.

[John Rumm]

Its amazing how a short while ago, dribble was posting all over the screwfix plumbing forum asking what was so special about the Remeha boilers since they seemed to be kits cobbled together from COTS parts. Now all of a sudden they are this months must have. I wonder what the special promotion at the plumbers merchant is this time?

The CDi seems to do a reasonable job of it with its twin temperature controls, from what I have been reading in the specs. Not sure about the benefit of the diversion kit - it lowers the system complexity outside of the boiler, but at the cost of fairly significant extra pipework in many cases.

Must admit I did not notice that requirement when I read the divertor kit manual the other day. Is that in the boiler install manual or elsewhere?

They are still parent to potterton, valor, main, and a bunch of others like heatrea sadia etc. So all the jokes are still valid ;-)

Yup that was the conclusion I came to. You can integrate it with the weather compensator as well, such that when running CH its under control of that rather than the front panel knob. The only downside I could see is that the weather compensator could not deal with multiple rad zones directly.

[John Rumm]

Cut with a hacksaw by any chance? We have heard what happened when you tried that, so no thanks.

[YAPH]

In the manual for the diverter IIRC, but that was for the i System (with the kebab heat exchanger), not the CDi (with the brick type)

I presume you're referring to the CDi series here John. Though I'm not sure if the PCBs are common with the kebab series, in which case those too may have a WC facility hidden away somewhere - unless it's disabled in firmware.

[John Rumm]

Yup, I was looking specifically at the CDi system boilers, as I think they were the only ones with the combination of split temperature operation and weather compensation... I will have to back track to work out where I drew that conclusion from though!

[Tim W]

YAPH wibbled on Friday 16 October 2009 01:50

What is a "kebab" HE? And why - is it made of things best not seen in natural daylight?...

[Doctor Drivel]

Please buy a W-B. They are expensive, not well designed and not that reliable either. PLEASE BUY ONE!!!!

[Doctor Drivel]

Dickhead, no, cut by the teeth of your Essex man's Bull Terrier. Forget the boiler, go and buy yourself some heavy jewellery.

[Doctor Drivel]

I had a look at the new W-B i range. The influences of Buderus are making an impact. I like the Buderus 600 range. The good point about the W-B diverter valves is that they are inside the casings, but not cheap at all. The company do not advertise the diverter valve option too well and appear not to want to offer it - a sort of under the counter secret. They have sold these kits for previous models with the alum' brick heat X.

With Keston and Remeha, the diverter is external and can be any makers, and the option of a cylinder sensor to modulate the burner is nice.

With the new i range W-B are getting there, a way to go yet. They have to get weather compensation as standard and update their control system offer OpenTherm.

As you noted, the diverter valve kit makes the system boiler a combi without the plate heat X - same diverter valve, etc.

Talking about diverters and combis. I had one job where they were all electric using a direct invented cylinder. They went to gas. The cheapest way was to fit a 25kW Avantaplus combi. The DHW side heated the cylinder using a Surrey flange on the Draw-off tapping and bronze pump on the return. The combi boiler can have the temperature of DHW side set up to 65C. It was set to 62C and the cyl stat to 60C. Worked a treat. The cylinder has 65C water pumped into the top of the cylinder ready for instant use, and heats top down. It heats the DHW in one long burn. From cold hot water is available in around a minute at the top of the cylinder. Instead of an external 3-way diverter valve and plate heat X, it use the internal plate heat X of the combi. The only extras were the Surrey flange, cyl stat and Surrey flange.

The Grundfos Home booster pump can be used as the bronze pump, which can be switched normally by the cyl' stat. A cost effective solution that means you can undersize the cylinder as DHW at the correct temp is put at the top of the cylinder and it heats Top down. 24kW is being dumped into the cylinder. A 100 litre cylinder would do two bathrooms as the cylinder and combi combine the energy within. It can just as easily be fitted to a vented cylinder. Simple compact and a doddle to fit.

[YAPH]

If you track back earlier in the thread I was referring to W-B boilers with kebab-shaped heat exchangers (rather than another part of their range which has exchangers milled out of brick-like blocks of ali).

[YAPH]

I buy quite a lot, actually, and have been fitting them since we went condensing in - what was it, 2005? Must have put in a score of them over the years (not all my work is heating, let alone boiler swaps) and not had a breakdown on one yet, only the funny Y-plan valve problem I described recently. The 24kW iJunior combi is under £770 with a standard flue kit.

As for well designed: I think the heat exchanger and functional stuff is good, but whoever designs details such as the case fixings could do with a kick up the backside.

[Tim W]

YAPH wibbled on Friday 16 October 2009 12:11

OK - I just couldn't quite picture it...

[YAPH]

I was thinking of doing that sort of thing with a very small unvented store in order to turn a bog-standard combi into a storage combi. In my personal experience the greatest pain of a vanilla combi is the fluctuation in flow to the shower (when I'm using it!) when someone draws DHW elsewhere (usually kitchen sink, washing up) so a very small store would do to iron out such fluctuations.

There's a Laing pump that Pulsar do that's suitable for DHW use. I've not tried it (though I had one of their condensate pumps and it was well-made) so I'd be interested to know if anyone has used them. I believe it's a forrin make (German?).

[Doctor Drivel]

Lately their reputation has slumped, as other makers are better than them. As I have stated, the product design is lacking, especially in the control aspects. They are getting there but a way to go yet. They are generally not cheap either.

I avoid until they get better in quality and design.

[Doctor Drivel]

Look at a 15 litre storage electic heater. Can be had for around £80-90. You could couple up two of them. Heat them with a bronze pump. So, a 30 litres buffer can be had inc pump for around £300. Also electric backup, but only 30 litres. Well you can just keep adding them to up the volume. :) It/they will act as the buffer and no G3.

What price approx? the Home Booster can be got for £112. "Bronze" pumps are near £200, The Home Booster should last as it will only be on for long reheats.

Few people realise that a combi/bronze pump can heat a cylinder and transform DHW delivery. The diverter valve and plate are inside and combis are cheap, sometimes £100 cheaper than the equiv system boiler.

[YAPH]

I am looking at one: it's a pre-loved one I rescued from a refurb, sitting outside waiting for me to find a Tuit!

Haven't seen new ones as cheap as you suggest, though.

Around £70 IIRC - I'm sure it was less than 100.

Heh! I know - I've put in some 24i junior combis where only a system boiler was required, for that very reason. Only the 12kW system is actually cheaper than the 24kW combi. And if you want something in between they've brought out 15 and 18kW, but they're about £1K - a third as much again as the 24k!

[ARWadsworth]

Is it the screws that hold the bottom of the front cover that you do not like?

Adam

[Doctor Drivel]

CCrunch may mean a price hype. A couple of them can make matters much better when using low power combi. I did put a few of these 10-15 litre unvented cylinders at point of use. There were in series in a secondary circulation loop. Pips stat on return to cyl. Worked well. Insulated and always DHW at the taps and nice DHW buffer on a combi. The furthest tap with three heater before it, was the bath. So, 45 litres of ready water under sinks to pour into the bath as the combi adds to it when being drawn off. Distributed storage. No G3, instant DHW at the taps, higher flows, electric backup of sorts and lots of space saved because of no cylinder. The combi needs to cope with a hot inlet. It switched on the electric at the three units (2.5 kW each), with a 28kW combi, over 35kW being poured into the DHW and 45 litres of storage.

Had a look at their site. I know the pump from feedback, rather than use. Those doing solar systems tend to use it. Well priced. The Grundfos Home Booster was used with 22mm pipe to reduce noise and pressure (it can lift up to 0.75 bar), although it comes with 15mm connections there is a 3/4" thread on the body. It can be connected to the combi and cylinder using 15mm pipe, which in this situation 15mm would have done, making it cheaper and quicker install.

I have used a combi for the shower only for high-pressure (about the only outlet you need high pressure, and all other on a low pressure combination cylinder, using a 3/4" ball c*ck to ensure a fast refill. Very cost effective and far cheaper than an unvented cylinder. Only prob' a mid-position or two zone valves needed.

[YAPH]

For me it's a toss-up which I dislike more: the bottom cover screws with their awkward angle and the ingenious way in which they can become dislodged sideways so you have to take the whole cover back off to reposition them, or the horrid little loose screws, just asking to be lost, going into U-clips just asking to get broken, positioned inaccessibly (on most installs) right on top of the boiler. Whenever I work on a modern Vaillant I'm consumed with envy for their simple system of loosen one screw, press 2 clips and off pops the cover.

Grrrr!