What's the current combi boiler of choice?

I'm beginning to despair with my 12yo Alpha combi boiler, so am thinking of replacing it. Rather than go with the recommendations of the fitter (if I do employ a fitter, I may diy), I would rather have a few opinions on what is the current best value/most reliable boiler out there. Pretty low consumption - only 6 rads, though i do like to have a shower when I get home from work, so must be able to deliver enough water. My current one is 24kw iirc, and has been generally fine delivering hot water.

Thanks for any thoughts. Alan.

Reply to
A.Lee
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Personally I fit Worcester-Bosch, mostly Greenstar 24i Juniors. They're at the lower end of the price range for decent boilers (cf Vaillant) and W-B don't have any reliability issues with their boilers (not that I know of anyway) or have blotted their copybook giving victims of boilers with disastrous reliability problems the runaround denying the problem exists (Google "Potterton Suprima problem").

If you DIY with a fitter for the gas stuff get your person lined up before you start and make sure they're happy with the arrangement, rather than expecting to get someone in when you've already done some of the work.

Reply to
YAPH

Thats the boiler which has the vertical heat exchanger that is pulled out to service it? Its also the same one which the baffles 'weld' themselves into the heat exchanger so its impossible to ever clean inside it! Only done one of these 3 years ago and apparently its now making horrible noises and will no doubt have to replace at somepoint soon.

Reply to
Dave Starling

Am I right in thinking that Vaillant is still the make of choice if price no object (within reason)?

Reply to
GB

What about Viessmann? I've recently installed mine - a system boiler - and it's beautifully made. They do a similar combi.

Reply to
Dave Plowman (News)

Dave Plowman (News) coughed up some electrons that declared:

I'm glad to hear that as I've asked the local gas fitter to quote for a Vitodens 100 Compact (he's also on the Viessmann list of trained installers).

He did spend some time trying to sell me a weather compensation system and a pressurised system, though once I'd knocked it into him that I was specifying both a vented and a braindead but efficient and reliable boiler to drive a heatbank, he gracefully gave up and recommended the 100 which concurred with what I already thought.

Wait to see what his quote looks like...

Cheers

Tim

Reply to
Tim S

We had an Alpha CD32C fitted about two and a half years ago and it's been brilliant. Mind you, only about 6 months of the 3-year warranty left so we'll see what happens then :o)

Reply to
John

I hedged my bets by installing both weather compensated and a room stat - and can swop between them in software. Not had poor enough weather to decide which one works best in this Victorian house with solid walls - otherwise well insulated.

My Vitodens 200 system came with an internal pressure vessel for the primary so I converted from open vent - but kept the header tank fed hot water system.

Reply to
Dave Plowman (News)

Dave Plowman (News) coughed up some electrons that declared:

Heh - I'm working the other way around, mains pressure hot water and vented rads/boiler primary. Hot water may be limited as I'm measuring about 35-50 l/min flow rate at the mains (through a tap, so it's probably actually a bit better, calculations suggest it should be nearer 50 l/min). But later on (when I have a reason to dig holes in the drive) I can uprate the mains pipe if I want.

My feeling is that if I'm using a heatbank, it will be better (=more efficient/faster) to offload the boiler's output directly into the mass of water in the heatbank and not put a coil in the way, especially at the temperature that the boiler likes (fitter said output max of 65C for best effect). My theory anyway... And I don't mind a little header tank in the roof - somewhere to put the chemicals in easily.

He was also trying to sell me a magnetic magnetite trap - never seen one before. Have you?

I'm going to put the cheapest 210 or so litre DPS heatbank in I can manage (price varies massively with short and fat vs. tall and thin and I'm building the space to house it, so I get to choose the cheaper format, which apparently is tall and thin).

Boiler control will be a simple hysteresis loop (with a very simple DIY'd relay logic controller) between twin tank stats and possibly a timeswitch to knock it off overnight (this may be pointless - once the tank is hot, I reckon it ought to manage to stay within the hysteresis loop for 6 or more hours)

Hot water is demand driven and the rads will, provided I don't have any budget-sucking problems with something else, be done with a Honeywell CM-Zone controller (several zones, to be decided). I believe there is a weather compensation bolt on for those, but I don't know if it's worth it.

Cheers

Tim

Reply to
Tim S

Was it one with the machined rectangular block of alloy heat exchanger or the conical cast type?

Reply to
YAPH

[snip]

I'd check with Viessmann before going down this route. I've a feeling it will invalidate the warranty. But can't be arsed digging out the installation book at this time of night.

Reply to
Dave Plowman (News)

Id recommend you get the CM-Zone through a merchant who will take it back if you dont like it. My experience was that the head units were noisy and would often do their exercise to measure the plunge of the trv pin. Was loud enough to wake a light sleeper. Also the range of the transmitters was much less than advertised - some of the head signals weren't received through a couple of brick walls. Seems a great idea let down by poor execution. Thankfully PTS took it back with no restocking charge. I'd say use standard trvs and something like an s-plan setup and keep it simple/stupid.

Also re the Vitodens 100 - the heat exchanger is a right sod to vent, even if the system is sealed. You need some way designed into the system to pass mains pressure water through it when filling. Even then it takes a good hour before the the flow switch will work ok for the burner to light.

Reply to
Dave Starling

Its the conical cast type. I think it was the same design style as the buderus which WB bought out.

Reply to
Dave Starling

Whiteley Brothers?

Reply to
Frank Erskine

Dave Plowman (News) coughed up some electrons that declared:

I'll be reading the installation manual too - but why do you think that Dave?

I'm going for a boiler designed for open vented use and the mains pressure water is generated in a heat exchanger by the heatbank - it's not a combi boiler, if that's what you're thinking?

Cheers

Tim

Reply to
Tim S

Dave Starling coughed up some electrons that declared:

That's interesting - thanks for the warning. I *could* always by one controller/HR80 pair and try it in our rented house for a while and see how the family cope.

What I'd love to do is make up a little embedded ethernet-mains relay and another ethernet-thermostat+display+buttons panel, stick a pair in each room (relay controlling a zone valve to the rad) and programme them to:

a) Be simple and locally controllable;

b) Respond to a central programmer, an "embedded" (form factor, but actually a full on PC) system with an LCD panel running linux which provides a central one-stop-shop for control and a web interface.

It wouldn't be that hard (I already do linux *and* AVR microcontroller programming), but as always, it's finding the time...

Perhaps it might be wise to have a well placed drain c*ck or two, which can be used to blow some mains water in with a hose. Won't hurt the system, it'll just end up coming out of the header tank overflow.

Ta

Tim

Reply to
Tim S

If it's the same as the 200, it has a filler/drain already provided since it's designed for a sealed system. I've had no problems filling mine despite doing it several times. ;-) Bloody lead free solder.

Reply to
Dave Plowman (News)

Dave Plowman (News) coughed up some electrons that declared:

Ah - found it in one of their documents:

"... Vitodens 100 Compact is perfect for new installations and boiler replacements on traditional open vented systems such as ?S? & ?Y? plan installations. Open vented systems make special demands on the heat exchanger and all of these have been taken into consideration in the design of the Vitodens 100 Compact, to ensure the quality, performance and reliability you?d expect from a Viessmann boiler."

It seems many of the models are for sealed systems, but this one (the one recommended and the one I was looking at) is the exception.

Thanks for raising it - it's good to check these things.

BTW, did you really need lead free solder? (Was it on the potable parts) I'm using 60/40 on the heating and lead free only where I need to.

Cheers

Tim

Reply to
Tim S

Worcester Bosch - pay attention in the back there! :-)

Reply to
YAPH

Right - I've looked at the instructions for the 200 and I was correct - sealed only.

It is indeed. However, although I was against a sealed system I'm now converted. Can't think of any advantage of open - apart from adding inhibitor etc - but this is really not much more difficult using a concentrate via a rad bleed. And it does make filling so much easier - no airlocks. Of course the 200 includes an expansion vessel - so no additional expense there apart from some pipework mods.

I ran out and it was all I could get. After discovering a couple of leaks in 'awkward' joints and having to re-do them I went back to leaded.

Reply to
Dave Plowman (News)

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