Heat Banks

[tsoutherwood]

Ok - so not a one off.

Thanks anyway...

Cheers
Tim

 

[Biggles..]

I've used Richard Baker at DPS a few times and can recommend their products. From the ones fitted so far i've had no hassles, the xtra costs seem quite justified in the build quality of the units.

The only thing i'd say which is from a personal point of view; i dont like the Tectite fittings they use in some areas of construction.

Lee

 

[tsoutherwood]

Hi,

I have spoken to DPS on the phone and they are extrememly helpful - a company that deserves, by it's attitude, not to go bust. Unlike some.

*cough* Gledhill *cough*

But... By my initial guestimates, I'd be paying perhaps an extra 800 quid for the priviledge. This is a bit of a high margin and I do have to watch the costs in this renovation project. And I still don't like the way the DHW is done - needless excessive circulation of the primary water (and it's resultant impact on stratification). They're starting to get that right on the Zedstore (see www.heatweb.com). Gledhill had the best solution IMHO using a variable speed pump and electronic feedback from the DHW output on the plate.

Agree on the Tectite fittings - wouldn't be much harder to use compression.

Cheers

Tim

 

[BigBurner]

BB,

I have to say, when you don't lose the plot, you're worth listening to.

I don't loose the plot. I am always spot-on.

 

[ajstoneservices]

[/quote] I am always spot-on.

.

You may well be, but biting back like a mad dog doesn't make for worthwhile reading and the good you have say gets lost.

 

[BigBurner]

I've used Richard Baker at DPS a few times and can recommend their products. From the ones fitted so far i've had no hassles, the xtra costs seem quite justified in the build quality of the units.

The only thing i'd say which is from a personal point of view; i dont like the Tectite fittings they use in some areas of construction.

Lee

The reason they use push-fit Tectite fittings is that they do not work loose in transit.

 

[gordonspants]

Hi, re the sensor pockets, they're just tapped holes in the cylinder into which you can screw a sensor pocket as supplied with a thermostat.

Point to note is if you have coils and 3 immersions, things may get tight in there - be interesting to see if it's physically possible to get everything you want in the right place heightwise. 9kw is a big electrical draw too.

Mine is 2 coil, I have now decided to flip and use middle for solar, bottom for wood after reading a navitron post - when do you need least heat - summer. Genius. I think
Rads are direct with return at bottom, boiler is direct tapped top and bottom. Boiler gets stupidly cold water sent to it when it first fires up - I would consider a 3 way valve next time to control return temp as BB has said, lengthening the condensing even more.

Re "Gledhill had the best solution IMHO using a variable speed pump and electronic feedback from the DHW output on the plate. " - that IS clever. Very clever - I'm going to have a google for that I think, as it's something I think would be very worthwhile as an upgrade - a downside I see on my setup is the shunt pump circulation from running a hot tap slowly for a few seconds *could* knacker any stratification.
My plate shunt pump was specced by advance as a grundfos 25/60 - which I bought from ebay, then it died within hours. Replaced it with an old 15/60 circulator pump running on low speed, which has been fine - hot water all ok, and water returned down to the bottom of the store seems cool-ish. On the flip side as I've said previously, get the hot water side heavy duty enough, and stratifiaction is irrelevant. A guy on ebay has been selling plate X's that look the same as mine - I think he's in the US from memory - may be worth pricing one up.

DPS are expensive, and everyone who's had one seems impressed, but then I'm not a pushfit fan either More of a tightwad than anything Pushfit's too expensive - have you seen the price of a new ceiling and carpets.

Advance were fine for me, updated re delivery, arrived as promised, and backup was excellent - a guy called Geoff dealt with me start to finish - may be worth asking for him.

The computer stuff sounds very clever, as in the live monitoring link posted previuosly - one thing stores etc need is (simple!!) computer control - being able to say for instance "outside temp = x, therefore solar input likely at xx hours, therefore gas boiler hold off" would be well worth having.

 

[gordonspants]

I really don't type very fast do I
BB has come up with some very useful food for thought, and without that I perhaps wouldn't have got this far.
So thanks very much, I appreciate it
I want solar because I reckon you can do it on the cheap and I also have quite a bit of free wood, so a combi boiler or an unvented cylinder ain't much use.
Relax - it's just someone elses plumbing, not the Gaza strip

 

[ajstoneservices]

Relax - it's just someone elses plumbing, not the Gaza strip

.

Not quite as civilised here at times as the other forum is it.

I agree BB's thoughts on thermal stores do make sense even if it riles others.

 

[tsoutherwood]

Gordonspants wrote:

> Hi, re the sensor pockets, they're just tapped holes in the cylinder into which you can screw a sensor pocket as supplied with a thermostat.

OK - I see. 1/2" BSP I think I saw one. I think Dallas chips (which look like a 3 pin transistor case) are probably small enough (low thermal mass) that makign a 1/4" hole in the insulation and coupling them to the tank wall with a bit of grease would be sufficient.

Sensor pockets for real thermostats though.

>Point to note is if you have coils and 3 immersions, things may get tight in there - be interesting to see if it's physically possible to get everything you want in the right place heightwise. 9kw is a big electrical draw too.

Agreed - but I'm going for a largely direct heated design - everyone uses the same water. The only coil will be down the the bottom 25% fo optional solar. I think it would be practical to have 3 bosses above this.

>Mine is 2 coil, I have now decided to flip and use middle for solar, bottom for wood after reading a navitron post - when do you need least heat - summer. Genius. I think

Cool. I don't have the option for wood as I need the tank on the ground floor, which rules out gravity circulation.

>Rads are direct with return at bottom, boiler is direct tapped top and bottom. Boiler gets stupidly cold water sent to it when it first fires up - I would consider a 3 way valve next time to control return temp as BB has said, lengthening the condensing even more.

Agreed completely - I'd have 3 port blender valves on rad circuit and the boiler circuit.

> Re "Gledhill had the best solution IMHO using a variable speed pump and electronic feedback from the DHW output on the plate. " - that IS clever. Very clever - I'm going to have a google for that I think, as it's something I think would be very worthwhile as an upgrade - a downside I see on my setup is the shunt pump circulation from running a hot tap slowly for a few seconds *could* knacker any stratification.

The Gledhill solution used a Grundfos UPR series 3 wire pump: that's live. neutral and speed-control. It's obviously a rare series - can't find data sheets on Grundfos' web site for UPRs. The speed control may be an analogue voltage (unlikely but possible), pulse-width modulation (more likely with a DC motor, but we don't know what the electronics in the pump is doing) or possibly a simple triac trigger pulse, so you'd need to pulse on a phase angle relative to the mains sine. Any which way, it will need a small controller board to turn a sensor reading into speed control with a negative feedback: hotter the tap water, slower the pump goes and vice versa.

>My plate shunt pump was specced by advance as a grundfos 25/60 - which I bought from ebay, then it died within hours.

Would a Grundfos Alpha self modulating pump help with your setup? I can't remember exactly how you are controlling your DHW - but if you're limiting the flow in the primary side of the plate, a pump that drops speed in response to restricted flow might be interesting.

> Replaced it with an old 15/60 circulator pump running on low speed, which has been fine - hot water all ok, and water returned down to the bottom of the store seems cool-ish. On the flip side as I've said previously, get the hot water side heavy duty enough, and stratifiaction is irrelevant. A guy on ebay has been selling plate X's that look the same as mine - I think he's in the US from memory - may be worth pricing one up.

Thanks - I'll look out for those.

> DPS are expensive, and everyone who's had one seems impressed, but then I'm not a pushfit fan either More of a tightwad than anything Pushfit's too expensive - have you seen the price of a new ceiling and carpets.

>Advance were fine for me, updated re delivery, arrived as promised, and backup was excellent - a guy called Geoff dealt with me start to finish - may be worth asking for him.

I agree - I think DPS look like a professional firm.

>The computer stuff sounds very clever, as in the live monitoring link posted previuosly - one thing stores etc need is (simple!!) computer control - being able to say for instance "outside temp = x, therefore solar input likely at xx hours, therefore gas boiler hold off" would be well worth having.

Yes - I was thinking along those lines. Even something as crude as "it's night, so use the boiler" and "it's day, lets leave some cold in the tank for solar" would be slightly smarter than nothing.

I like computers (I program AVR microprocessors for fun - and they're just the thing for a job like this - though equally so are PICs)

But, I don't trust 'em either. So order of business is make something simple and functional quickly. Later, I'll try to play and augment (not replace) the dumb controls.

Good thread this - it's good to see some pioneering spirit still alive

Best,

Tim

 

[BigBurner]

a downside I see on my setup is the shunt pump circulation from running a hot tap slowly for a few seconds *could* knacker any stratification.

Use a Danfoss RAVK valve. See:
http://www.heatweb.com/pdf/DPS/ZedStoreDistrict.pdf
This reduces excessive pumping into the cylinder, destroying stratification.

A 3-port Danfoss RAVK diverter valve will do with a simple CH pump - the other port on the 3-way valve can loop back to the suction side of the pump. Have an adjusting valve on this leg. Then the valve only opens enough to allow the correct amount of water to flow through the plate.

Having the solar panel on the bottom coil means the solar panels will work more often at the bottom of the store as it is free from purchased fuel influences of gas and sold fuel. It could be pumping heat into the cool bottom of the store even in the heating season.

Using the upper store coil, at times the store may be up to temp via purchased fuel, and the solar panels see no temp differential to operate the solar pump.

 

[tsoutherwood]

Re: The RAVK - yes, this does seem to be the simplest way without electronics. Wasn't my idea - someone on uk.d-i-y came up with that too.

Personally I would couple that with a self-modulating pump (their common enough) so teh pump doesn't thrash it's nuts off against a trickle flow.

Cheers

Tim

 

[BigBurner]

Re: The RAVK - yes, this does seem to be the simplest way without electronics. Wasn't my idea - someone on uk.d-i-y came up with that too.

Personally I would couple that with a self-modulating pump (their common enough) so teh pump doesn't thrash it's nuts off against a trickle flow.

Cheers

Tim

A Smart pump's control may conflict with the control of the RAVK valve. This may result in hunting. Using a 3-port RAVK looping back means the pump is always on full flow, although not always through the store.

 

[tsoutherwood]

Ah - A 3 port version. Fairy-nuff. I was considerign a 2 port version.

I can see that will be fine.

Cheers

Tim

 

[gordonspants]

OK - I see. 1/2" BSP I think I saw one. I think Dallas chips (which look like a 3 pin transistor case) are probably small enough (low thermal mass) that makign a 1/4" hole in the insulation and coupling them to the tank wall with a bit of grease would be sufficient.

Yep, 1/2" std thread. My casing is plastic coated steel then foam under - may be tricky making neat holes in the steel case.

Would a Grundfos Alpha self modulating pump help with your setup? I can't remember exactly how you are controlling your DHW - but if you're limiting the flow in the primary side of the plate, a pump that drops speed in response to restricted flow might be interesting.

Good thread this - it's good to see some pioneering spirit still alive

All I have is a flow switch on the water feed to the plate, switching on the shunt pump - so any smart pump would only work if something like the Danfoss/DPS throttling valve is used. I assume it's infinitely controlable from 0-100% - but surely to get it spot on you'd be into different response/feedback curves and stuff to give correct temps at half flow, 3/4 flow etc? Theory then is hot water takes only the bare minimum amount of energy required from the top of the store, dumping (in theory!) only energy-free cold water back at the bottom. Clever!

A Smart pump's control may conflict with the control of the RAVK valve. This may result in hunting. Using a 3-port RAVK looping back means the pump is always on full flow, although not always through the store.

The DPS link showing a RAVK valve looks like it's just 2 port - which would be simplest plumbing-wise as opposed to 3 port - just control the RAVK valve opening dependant on hot water temp, then throttle back a smart shunt pump as req'd to keep hot water temp reasonable - still need a tmv though for safety. You're right, hunting could really screw it up, so maybe a standard circ pump would be better - and cheaper, which is A Good Thing As long as it never fully shuts off, that'd work.

But before any of that, antistratification within the tank would be better and cheaper - mine has no antistrat eg spreader pipe with holes in, but works ok. Possibly turning my CH, boiler and shunt pumps up to eleven would really mess things up, but as it is with all pumps on speed 1, top generally stays hot, bottom generally 10 to 30 degrees cooler. The law of diminishing returns ie excess complexity vs money saved comes into play as well! Unless your hot water is heated via an underdesigned internal coil, it really doesn't matter that much - the energy doesn't get lost, just misplaced - but that statement may come back and bite me in the a.se when I do get solar and woodburner in and running, as they both need a hefty temperature difference ie cold store water to work well and transfer maximum free energy to the store. 300l of tepid water in my store won't help!

My brain is working again after the xmas break