Copper pipe and cabel - cheaper when?

[BigWallop]

It's "Cable" the subject is on about. I thought you wanted Copper Pipe for your Cabela

. :-)

[John Rumm]

Sounds more reasonable i you are doing all the leg work... having said that, if they are turning work away then there is no reason for them to take the lower paying jobs.

Sure...

Yup

Pressure drop test before you start - saves hours trying to figure out where a leak is that you did not create in the first place. Do a let-by test when do for completeness.

Yup.

(12m of 22 was the limit (only needed 6) for my 35kW boiler IIRC... with less power you can have a longer run obviously).

Yup

Yup

The makers instructions will probably claim not - they did on mine. Although IIRC, Andy G has posted here in the past about discovering how far from optimal the factory presets can be.

With a basic "out the top and through the wall" flue it would be hard to get it wrong as long as you fit the gasket and do up the screws etc.

All sounds ok. Obviously follow the instructions for commissioning.

[Tim S]

Hi John,

Thanks for all that :)

John Rumm coughed up some electrons that declared:

Proposed boiler is only 24kW, so that should be fine.

I'm tempted to add the short vertical (1m or so high) optional stack - partly to get the plume out of the face of passing people and partly to remove the admittedly tiny risk of any combustion products leaking back into the roof space via soffit vents.

Righty ho. Hire is an option at 100/week for a Kane, or ebay has bottom end instruments for about 250 with cal cert. Given the overall saving, might be worth buying and reselling afterwards.

Jolly good - that's what we like to hear :)

One of the benefits of Viessmann is their documents are all online, including the installer manuals (which appears very thorough). No masonic-society approach, and I've spoken to their tech support twice and on both occasions they've been excellent.

I reckon I should be able to do this in about 2 days (with lots of double checking), given everything else being ready. Actually it will save time, because I'll do it at the same time as the thermal store, rather than lashing the current boiler up to it first.

OK - I'll research this a bit more, but I think matey just priced himself out of the job (maybe he wanted to).

Once again, thanks John

Cheers

Tim

[Dave Plowman (News)]

I've found their documents assume a thorough knowledge of the product - more a sort of reminder of the training course you've supposed to have been on. I did two 'mods' to mine - added weather compensation and an extra remote programmer (was used to having one on the kitchen wall rather than having to go to the actual boiler). There were no step by step instructions on altering the software to incorporate these in the instructions - I ended up having to ask their tech guys. Who luckily are very helpful. And it was so complex I can't imagine the average installer carrying around this information in his head.

[Tim S]

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

Hi Dave,

So did you find any problems during the basic install (before you added the extra mods) - or are there any gotchas worth knowing about?

I'm fitting the Vitodens Compact 100 which is about the simplest unit they make (and purposely so).

Cheers

Tim

[Dave Plowman (News)]

No - that part was ok. Only slightly strange thing with the Vitodens 200 was they didn't show the safety overflow - despite *all* the other pipework being very clearly indicated in the installation instructions.

My feeling was that a system boiler would suit my needs better - especially if it came to the point where someone else had to do fault finding etc.

[Tim S]

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

Thanks Dave. I'll look out for weirdnesses like that,

I agree. Though a thermal store looks like a hideous beast with all the pumps, etc, it's actually a fairly modular system.

My reckoning is: store tank will never fail, pumps are bog standard Grundfoss units, mixers valves are probably the most esoteric part. I'm not even going to bother with DPS's fancy controller module. I'd rather take the two tanks stats via a relay box back to the boiler along with the boiler pump. Power for the HW circuit pump and room-stat-timer control to the rad pump.

Immersions are 3kW units (bog standard) rather than the slightly odd 6kW option that needs external dry-overheat protection.

So, despite it being a very custom system overall, absolutely everything likely to be a maintenance item will a standard device. Same with the boiler. One circuit, full power when asked for, don't even need a modulating burner AFAICS, though that's probably hard to avoid.

The only thing I'm not bothering with (probably) is the UFH options. I'll have a max of two UFH installations and I reckon it's probably easier to put in a local mixer/pump for each one off the rad circuit. But I'm open to reconsidering that one.

Cheers

Tim

[Tim S]

Clint Sharp coughed up some electrons that declared:

Aye, their web site says " Latest competitive prices, inline with commodity fluctuations.", 110 quid for 30m of 22mm

Seems to have been at that price for a while - perhaps it's already seen a lot of the drop?...

Cheers

Tim

[Dave Plowman (News)]

My feeling was that modulating burners and variable speed pumps all under the control of the main microprocessor are desirable to increase the overall efficiency of the system, as are sensors rather than stats.

[Dave Starling]

Thats not competitive at =A33.66 / metre. If you can drag an OAP to the orange shed on Wednesday then you can get it for =A32.66/metre. Ironic as they are both owned by the same group.

Dave

[jim]

tim thanks for the rundown - can i also ask what the twin tank stats (& your relay stuff) give you over a single one? also on the DPS designer thing - what are the "upper detect circuit" and "lower detect circuit" about?

cheers Jim

[Tim S]

jim coughed up some electrons that declared:

Hysteresis. eg, boiler doesn't fire until the top stat gets cold and keeps firing until the bottom stat gets hot again.

All single stats have some natural hysteresis, but in this application it's relatively tiny, so with a single stat (near the bottom, above the solar coil) the boiler would heat up the tank, then keep switching on and off in fairly short cycles everytime a little heat was taken out of the tank.

This is fine for electric heaters, but not so good for boilers.

DPS will sell you a control unit that handles the twin stats, but it does (IIRC, I discounted it fairly early on) more other things than I need, it's a proprietary component (so's my contoller, but mine will be assembled from DIN relays and terminals, so it's easy to repair).

You don't want the tank becoming 100% depleted by the radiators, so the take off for the rads is not at the top - you always want a reserve amount of hot water to make, well, hotwater for the taps. The circuit that drives the plate heat exchanger (for taps) is taken off right near the top, so you always have 1/3, maybe 1/2 (depending on exact design) of a tank of hot water ready for taps and showers.

Cheers

Tim

[Andy Dingley]

Day after your "tracker" mortgage drops to follow the new base rate.

8-(