I have known plate heat Xs to have holed. Not a lot, only one. It can happen because Murphy's law says so. If it does water all over the place.
Unvented cylinders have safety devices. The Pandora does not. if the cylinder fills up the diaphragms will bust in the expansion vessel - the weakest link. The expansion vessel open to atmosphere is to prevent sludging and evaporation of water as it is not open to the atmosphere.
Geldhill's Sytemate could be filled via an F&E with no ballcock - filled by hose. The water evaporated so the customer needed to top up.
A MAN will go down to 3Kw if you want to spend that amount for one. The average is around 6kW.
Boiler cycling is always a bad thing. It will cycle, as once up to temp the heat input to the house can only be 0.25kW. The problem is reduced, however it is still there, not eliminated.
Look at few boiler configurations then.
You are in the Jurassic era. That was not my experience of W-B unless they have upgrade their controls lately. I am not impressed with their range at all. They need updating.
I have explained the dual-temp boiler, on another thread. The MAN is one, as is the Keston Qudos. Vaillant can be one with an expensive add on.
This thread and this explains a lot which confuses our Essex man. "Recommendations for a decent boiler with external temperature control?"
"The best value of any and very well specced boilers are the Remeha Avantaplus range. Broag. Remeha have just bought out Baxi and they are well placed in the UK now and have been for decades in commercial. Do a search on this group and all will come up. It is a dual-temperature boiler with Integrated outside weather compensation. When DHW calls the boiler runs up to maximum, or whatever boiler stat is set to, and when on CH operates from the weather compensator. Then very fast DHW recovery. The boiler also has OpenTherm control.
The cylinder stat is connected "directly" to the boiler, as is a 3-way "diverter" valve (not mid-position junk). The cyl stat says I need DHW, the boiler moves the diverter valve and runs up to maximum temp - or what you set it to - for rapid DHW reheat. Once DHW is satisfied, the boiler moves the diverter valve top CH and weather compensation takes over.
Yes. Comes as standard.
W-B are lacking. Remeha, Atmos, MAN, etc lead the way in control. Keston are the only UK maker with a decent control system on their boiler range (crap boilers though - they were good). I believe Vaillant have an inferior control system to the German models. Continental models all tend to have OpenTherm control.
A BIASI model comes with an integral weather compensator, but they do not sell the outside sensor. The sensor is the same temp range as one of the water sensors and can be fitted in weather proof box outside and weather compensation. Many do not push weather compensation, as the tech depts do not like the service calls from plumber who haven't clue what it is.
The Avantaplus is taking off and sells like hot cakes. They bought Baxi. They advertise heavily in trade mags pushing the products. They are "very" reliable, with few plastic bits. They are the best bang-for-buck boilers around by a mile. That may change, but now they are. They are better than Vaillant.
I do not rate W-B, except their Highflow combi models, which could do with better control systems (like integrated weather compensation) - it is a compromise as they do deliver the DHW and canm be DIYed.
The only way you can minimise the heat loss via flues is to have "long" plastic flue extensions with some bends. It is difficult for heat to float out to atmosphere then.
Boiler heat exchangers are not insulated, although I see a poor attempt in some casings, which is mainly to supress sound rather than stop heat leaking out.
You could screw a pipe into the top of the pressure vessel and run this to outside. Then if the plate does hole there is an overflow. But that defeats one of the advantages shouted from the rooftop by DPS - no overflow or pressure discharge pipes needed to atmosphere.
But, it can be run into a tundish and into an internal drain via a HepVo trap, so no building fabric penetrations.
I have an attitude of not accepting people's theories when the only supporting evidence is "because I said so", and "I am a pro (in something unspecified)". Some latitude I grant to particular individuals who have demonstrated exemplary accuracy and reliability in the past (for the avoidance of doubt - not you). I appreciate that you would rather people in general don't question you assertions and accept them blindly, but that is not my way. I don't think it has much to do with living in Essex.
I have no doubt that your design would have merit in some circumstances. However you have not presented any *compelling* reason why it would be better in mine.
No, you knocked up a diagram for Phil, at his request. You will note that he thanked you for it as well.
However not wishing it to go to waste, I will include it in an extension of the heat bank wiki at some point, along with other designs and options.
Ah diddums. Sorry did not want to make you feel (more) inferior.
Lack of understanding was not the problem. As I explained before; I understood your points, I just did not accept them all. This was either because you failed to present evidence / logic / viable theory to support them, or because they were erroneous.
That is also non sequitur, whether someone is able to understand someone else's point has little or no bearing on whether they charge for their skills.
I counter what exactly? Your adherence to pet theories and beliefs that have that in many cases were either doubtful in the first place or have ceased to be relevant due to technological progress.
Only three? Wow this is a new found restraint from you.
If I drew you a diagram, would you go and do it?
I fitted a 15 lpm one, that during my ownership worked very well. The relevance of this is what exactly?
What you are suggesting is more expensive, and seems unlikely to give any tangible increase in performance for my application, while at the same time not presenting the user controls so that they operate as I would like. In my experience, starting with a design that does not match the requirements is a good way to "make a mess of it".
Martin Bonner wibbled on Thursday 15 October 2009 13:44
Exactamundo :)
Which is why the words "MicroSoft" and "Automotive safety system" scare me. You can perfectly well make safety critical computers, but it takes a whole different set of skills, hardware and operating systems (if any) and approaches than most of the dismal hack merchants who peddle software would every likely to know.
You have an attitude FULL STOP. I have explained many things to you twice and you respond clearly not grasping the point. Not only that you do not ask for clarification you deride on points in a subject you know frig all about.
YOU HAVE A CLEAR ATTITUDE. You are a DIYer and one who can't gasps many technical aspects in field that is pretty alien to you. Just do as I say and you will get a top system, otherwise just spend a fortune on something that gives no more than an unvented cylinder fitted by the plethora of know-nothing bathroom changers around.
The big snag of course is the interface from nice friendly logic to big nasty mains required for valves, pumps, boilers etc. Those could well cost more than the entire Arduino setup.
My current 4 zone 2 pump 1 boiler with pump overrun CH/HW control system is done with wiring and relay logic. It's not 100% on the pump overrun but it works. If I was doing it again I'd go for a PLC with enough I/O then the logic would be correct on the pump overrun and would have half a dozen DPDT relays involved... I might look at something like an Arduino but that interface problem raises it's head, a PLC is just a large block with lots of mains rated I/O...
Did I tell you about the demo Jaguar we played with once? I was working on a project called Road Traffic Advisor which basically was a short range microwave link from an overhead gantry to a tag in a car passing under. Loads of different companies involved with varied agenda. Anyway, one test vehicle we had was a jag with all sorts of technology crammed into it for experimental purposes (the boot was literally full). The slightly less reassuring aspect was the high priority CAN bus, that provided fly by wire throttle, brakes, and steering! Not a mechanical linkage in sight...
Dave Liquorice wibbled on Thursday 15 October 2009 14:36
No ;->
This perhaps:
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's true they're not cheap (nigh on a tenner) but I reckon you could drive those directly from an AVR (14mA coil current at 12V). Or a cheaper relay and a transistor?
Alas no. The vast majority of embedded systems I have done have usually been on someone else's bespoke designed hardware (and frequently the poorer for it!). There is a whole world of small cheap off the shelf controllers out there that it could be fun to get to play with.
It looks like it could sink enough current for reasonable sized relays.
(I once had to use a daft 8031 microcontroller based hybrid (i.e. device, plus IO and external memory all on a 27C257 sized EPROM), that could not even switch a conventional bi-polar transistor by itself! We had to use MOSFETs on the output line, just to have it be able to flash a LED!)
Indeed, although ultimately its usually just a bunch of relays and a processor of some description to drive them. Its the programming environment that can make them more accessible and/or frustrating though.
John Rumm wibbled on Thursday 15 October 2009 16:18
You'll like AVRs then, which the Arduino is based on (forgive egg suckage - I assume you've not come across them?...). The C is very clean and the worst bit is reading the data sheet to load the configuration registers to configure each IO pin to one of umpteen and submodes.
After that, driving the pin is pretty much doing an "=" in C or a bit set if you desire.
Even the interrupts play nicely. And AVRs come from 8 pin 50p jobbies to 40 pin ones like this:
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flash, 4k EEPROM, 16k RAM, 20MHz and loads of features on board)
Those will drive 40mA per pin upto a max of 200mA total for the package, so easily 10+ well chosen relays.
Actually John, the reassuring thing is that there are a huge number of cars on the roads now that are fly-by-wire - or to avoid that being taken literally - 'drive-by-wire'. The remarkable thing is that there don't seem to be any incidents that can be related to this. Ironically the impression is that the aircraft industry seems to have more problems than the car industry.
To put this into context, it was a few years ago now. At the time this was the first time they had gone completely electronic on all the major controls IIRC. Had it have been a production car it would have been less worrying - but this was a lab hack basically with all sorts of non tested systems in there.
Had a slightly worrying discussion with one set of engineers, who could not understand why their software would sometimes crash on receipt of the first information message. They were supposedly displaying all the info we relayed to them from the microwave beacon on a nice little LCD screen. Alas they were taking the first four bytes of *any* message they received, and immediately attempting to malloc() that number of bytes from the OS (Windows embedded!) based on the assumption that they represented the size of the following message. We were suggesting that this was a risky strategy without at least verifying the message structure or checksum first!
Although to give credit to the flyboys, it is harder to fall off the ground. ;-)
So you mean "I have known one PHE to have holed". With respect, John, that's a statistically insignificantly basis on which to diss DPS' design. One might equally well insist on doing all water pipework in double-walled tubing and god-knows what other belt-and-braces measures on the basis of the small number of holes which occur in copper tube, brass fittings etc.
At the end of the day it's only water: we want running water in our houses and the price is that occasionally we will have it in places we don't want.
In the W-B kebab design the flue gases exit downwards from the combustion chamber, pass horizontally through the condensate separation device, then up to the flue/air inlet terminal. It is difficult for heat to float downwards, sideways and out to atmosphere. By contrast in the horizontal-axis heat exchangers of the super-duper Remehas and most other designs on the market today there is some way that a small amount of heat can escape by convection as you describe, but I don't think it is particularly significant given the low water content of the heat exchangers themselves.
I can put my hand on the casing of the W-B kebab heat exchanger and not need to visit A&E afterwards. I've come across hotter pumps.
I'd like to see them implement some sort of external control of flow temperature: this OpenTherm business seems (from the little I know about it) to be a way to go.
But I did look into the business of providing a suitable flow temperature for DHW even if the CH flow temp control was set down low (or even to its off/frost position) and it seems to me the facility is there (you just need to connect volt-free contacts to two pins on the PCB) but is only supposed to be accessed via their diverter kit. Which at £80 is not exorbitant, but they do then specify that you *must* use one of their front-panel programmers . In any case since the boiler was being installed in the attic there was no way a front-panel programmer would have been acceptable, but equally there was no problem in simply leaving the main CH flow temp control set at a suitable level for DHW also.
Except that it's a little less efficient than weather compensation. Which would be nice, but in the Real World (tm) (or at least that corner of it I have the dubious honour of servicing) a few % improvement in boiler efficiency is as nothing compared to other improvements which could be made, such as getting the customer to actually use their TRVs properly instead of leaving them all set up to max, etc :-(
So are Baxi no longer part of the group that includes Potterton & Main? We'll have to find a new nickname instead of Poxi-Batterton ;-) Any starters?
Sounds exactly like the W-B diverter valve kit. The system boiler is basically exactly the same as the combi with the PHE, the motor that drives the diverter (not mid-pos) valve and some pipework removed (and a chunk added to the price!). The diverter kit basically reinstalls the stepper motor and some pipework to provide a separate return for DHW from CH, and you link the cyl stat to the PCB directly (and the room stat to the PCB's normal stat terminals). (I guess the front-panel programmer interfaces to the PCB to effectively put the cyl stat and room stat in series with the programmer's controls.) When DHW is called for the boiler runs at 75C, otherwise at whatever is set on the front panel CH temp control.
Not much of a recommendation to me, given the track record of the (admittedly few) Vaillants I've come across. Though hopefully nobody's tech support depts could be as bad as Vaillant's: impossible to get on the phone, they actually recommended to me that the best way to get in touch with them was by email, from which they'd call me back in the next day or so (which they generally did).
Perzackerly =A350 for the an Arduino with ethernet. Then in my system 4 valves, 2 x pumps and 1 x boiler =A370 for the relays not to mention a rats nest of wiring.
It's a long time ago now but I looked at the Mitsubishi Alpha. Played with the PC software got it doing what I wanted without very much (if any) RTFM. B-)
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cheap but a neat one box solution with a display that could give friendly information about the system. Rather than having to use LEDs or neons on the real outputs (and all the extra wiring that entails).
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