Integrated woodburner, solar tubes, oil combi and underground heatstore.

[daftlad]

Page 13? Well above and beyond the call of duty methinks. No one should have to go through that.


 

What are you on about? EVERYONE should have to go through that and then be tested before they can post.
 
ta ta

[Rick O Shea]

I think I have a further 43 pages to go......... onward and upward.

[desperate]

Shouldn't that be "Downward and Outward"

Desp

[noelsquibb]

Way back in the mists of perhaps page 8 someone suggested  that the use of a large plastic  drum  would be part of the solution to leakage, if you were to start again would you consider this?

It seems to me (when skating on thin ice you might as well dance) that there are so many dissimilar materials  GRP foam copper steel paint solder and the frame that supports the whole device as well as the gravy,  etc etc you are getting into the biological elements of potential microbiological/electrical corrosion. Akin to a doctor  treating the symptoms of a second problem which are the result of the tablets being proscribed to sort out the first.

if you had the money would you consider dispensing with the rads and in the gravy pit using a matrix of copper pipe?

rick,o
I'm glad I managed to distract you.
If you had started off with frots epic though, you probably wouldn't have done this one ....
I read the whole wind n diesel thing and was so impressed I drove the three miles to track him down and sup his tea.
I agree it should be compulsory reading for all newbies prior to their first post, this ensuring 'suitable' inspiration.

Yup, if I was going to do it all again I would deffo use a 1600 litre roto tank at £164, http://www.dvfuels.co.uk/product.asp?pid=19 inside a set of manhole rings with two pack expanding foam filling the approx 4" gap between.

Not too worried about the biology as the gravy doesn't seem to be particularly life supporting and none of the water inside the three heat exchangers ever gets in contact with the gravy unless a leak occurs, then system pressure pushes the contents of the heat exchanger into the gravy.
The chemistry seems to be a different matter though. 

If I had the money    read on ...

[noelsquibb]

Well it finally happened, the weather got warm enough to stop using the woodburner and the lawn dried out.
No excuses then.
Time to see if the heat exchange array could be lifted out of its pit of chemical doom and reconfigured.
Plus the sooner its done, the sooner I can start harvesting photons.

Luckily, I connected the pipework so that there was always a compression fitting against the face of the tank, there's confidence for you.

So a bit of spannering, some switching, a diversion loop to bypass the diversion loop and everything's ready for the lift.

I dug out the record pics to see how I had slung it for the install and set up some adjustable tie straps then trundled my favourite toy into position.

It was surprisingly easy and even though one of the slings displaced its leg away from the radiator and got a bit unhooked, nothing untoward happened.
I even managed to load it onto the trailer lying on its side, thus creating a portable work platform, without snapping any of its pathetically weak plastic legs.
(The Lard Frot has sturdy legs by comparison )

So into the workshop for some serious tinkering at last.

A bit of wire brushing and a blast of compressed air demonstrated to me that the key weakness in the paint coated steel is the spot welds and all the radiators were suffering from the medieval skin condition to a progressive extent,  with the top rad taking most of the stick, demonstrating a progressive reduction on oxygen with depth.

[noelsquibb]

more pics

[noelsquibb]

So with a bit of pumping, the gravy was sent through the septic tank and into the self sown reed bed that has decided to inhabit the soakaway area. The next day ( thursday ) I was able to do a post mortem on the heat exchangers and the pit.

Heat exchangers as already noted, the steel rads were progressively pickling, the copper looks good though.
There does not seem to be any kind of pipe lagging that will retain its foam like qualities in the hot wet acidic environment apart from the rigid expanding foam, which has proven to be impossibly difficult to form around a curved pipe and probably will continue to expand anyway.

nice view from the bottom too

[noelsquibb]

as for the pit itself, there appears to be two problems with the grp  or maybe just the gel coat.
To explain the mess, the top part of the tank was done after all the plumbing was completed. While I was doing this I kept the tank full to stop any possible flotation. The ground water seems to be low enough to leave the tank empty at the moment so hopefully no ground water pumping needed.
Anyway its a mess at the top because the final layers of resin dribbled down the gel coated stuff below and on into the water.
Around the top few inches where the water tended to be most chemically active, there are brown and white powdery deposits of gawd knows what. ( where are the feral yoofs when you need em to run tests ?)

Below the discoloured areas there are splits or lens shaped flakes missing from the gelcoat that continue down for about 18" then seem to peter out.
The bottom 1.5m of sidewalls then looks good.
The base seems to have some bulges that when trodden on, split and release water, again looking like the gel coat separating from the GRP layers below.

[noelsquibb]

Good to see some rain today then.
No excuses or distractions, just good ole plummin.
Couldn't believe the cost of 22mm copper though, at £3.50/m inc vat 

Cant replicate the radiators exactly and as a result cannot get an easy air purge.
Decided to go for a single continuous line rather than parallel lines cos I couldn't envisage the flow distributing evenly through parallel pipes.
So mr ziggy zag seems to be the way.
I'm using lead solder cos Pontiff said so and enjoying the ease with which it flows.

mr ziggy zag -

spot the impostor -

[noelsquibb]

It all started to look a bit sad and lost at one point as I removed the entire upper metalwork.
Had to be done because the heat exchanger pipes that pick up heat for the DHW and CH were built around the steel radiators which were tilted both ways and the replacement 'rads' can only tilt one way if I am to get them full of water. Reckon I should fill from the bottom up, when the time comes.

All the soldering got a 6bar 1 hour air test, as it would be a bu66er to try and find which of the 200 joints was leaking.

Not sure what to do about the failing gel coat in the pit

Anyone got any suggestions ?

[daftlad]

Noel.
By changing from radiators to pipes you are reducing the surface are significantly. I know that copper transmits heat better than steel but do you think this change may be an issue? If it does turn out to be an issue then soldering some fins or something like that to the copper pipes could help?
Good stuff though, copper certainly has gone up to a silly price.
ta ta

[dhaslam]

Looks like you have osmosis in  the  fibreglass  tank which will lead to leaks.    Boats with this problem are normally just patched  with epoxy and that would probably work for a tank with hot water as well.     I met Hugo du Plessis the author of the standard  book on the subject a good many years ago. 

www.yachtsnet.co.uk/osmosis.htm

[sunandwindy]

From another thread Noel  made this comment about some pipework in an 'off the shelf' heat store....

sunandwindy

we are both trying to suss how much copper pipe is needed to create similar heat exchange potential as these gert lunks.

I recall the tube dia being 22mm and someone saying that this deformed tube has the equivalent of 1.5 skin area of same length smooth pipe.
When I tried to track some down it seemed to be rare and very expensive.

I think the coils in James' (fiddlers) pics are 150 dia, making the tube length about 10m
So a smooth pipe equivalent of 15m to give about the same heat transfer.
Im reckoning on double that for my heat input when I replace the steel rads and already have about 18m of pipe for each heat extraction loop ( all 22mm dia copper )

If I was going to build another underground heatstore I would put one of these -
Recycled Black Tanks  -  1520 litre / 330 gallons -  £250 inc vat and delivery
http://www.smithsofthedean.co.uk/Rain%20Savers.htm

inside circular manhole rings and foam fill the void between the plastic tank and the manhole rings to insulate.

The heat exchangers would all then be big coils and could possibly even be hep or speedfit pex type pipe for the heat extraction but would need to be copper for the incoming heat with potential to get hotter than 100c.

pm me if you want to know more about how I ended up doing what I did.

Sorry to hijack your thread James.  You found that leak yet ?

I too have been looking at the large black pvc tanks as my store, but before burying I would get several coats of foam sprayed on to it, then a coat of bitumen to help prevent ingress of water. The tanks occasionally come up in local farm auctions very cheaply, so I'll bide my time for one to come at the right price.

Looking at 'off the shelf' hot water immersion tanks the other day and it seems they have now cottoned on to the problem of creating gravy and pre-install anodes. Looking at your anodes, I was wondering if you used softer aluminium ones would help as I expect the bike sprocket is something like Duraluminium (not sure of the spelling, but basically a hard/tough aluminium), thus not working in the desired fashion. Perhaps the aluminium used in drinks cans may have been better, but thats painted one side

Its a shame the radiators didn't work (life span wise), however on that theme I disassembled my LPG boiler the other day (not used it for 20 years as toooooo expensive) as it was tooo heavy to carry down the stairs in one lump. The heat exchanger was made up of three cast iron lumps with lots of needle like things on it to gather heat from the flames. I thought these may be good to use in my heatstore as they wouldn't rust away very quickly, though I think I'll still run with yards of bent copper pipe (plans can change though   ....several times). I'm not sure about using speedfit pipe as the joints can be troublesum, potentially more so if one side of the 'O' ring is subjected to strange chemicalised fluids/water. Bit of a traditionalist me, I like soldered joints.

I used to work in a place where they used all sorts of extreme chemical and acids and a lot of their containers were PVC (roto moulded or welded sheets) and GRP, so it seems strange yours has de-laminated, though they may have used a thick final gel coat (actually its the first coat) on their GRP stuff. May I ask how many layer of glass matting you used as it may just be a matter of it not being thick enough? Presumably it was stranded matting, rather than woven matting?

That's it for now

Steve

[noelsquibb]

daftlad,
there may be less transfer potential but having looked at other heatstores, I reckon the potential to transfer incoming heat from the WBS will be ok, simply based on the amount of copper tube used.
If its a bit less effective, all that will happen is that the return temp will be a bit higher, not a big issue.
We tend to run the WBS by monitoring the top boiler temp so a bit less burn for a bit longer perhaps ?
The heat exchanger that is getting uprated, is the one that feeds the hot taps. Think I used 16m of 22mm dia copper for this, with it winding up through the tank. It actually works well if the whole tank is hot but not so well if the bottom heat had been lowered cos we've run the CH for a few hours. Although it would be up to the job if peeps would run the bath a bit slower....

dhaslam,
any idea what sort of epoxy resin and how it might be applied ? 
Am I getting confused thinking the resin used to build GRP is an epoxy ?

sunandwindy,
thanks for your interest and comments.
My anodes consist of three different bits of aluminium alloy ( no idea what other metals are in the mix ) and a big lump of zinc specially for the job. Easy enough to chuck in and hopefully not quite so essential with only copper tube and lead solder in the heatstore in future.
Interesting to learn that anodes are a regular item. Guess we all learn the same way though 
I would stay away from the cast iron and stick with copper, simply because I really don't fancy another chemical brew with further reliability issues and always failing when you need it most ....
Course, if I had some old cast iron boiler bits lying around 18 months ago, that looked like heat exchangers, I might have used em.

Regarding the GRP build up, I used two layers of fairly heavy stranded glass mat ( not woven ) and resined the main areas on the flat, leaving flaps of unresined glass mat sticking out beyond selected edges, that formed the internal corners.
As I was not working from a mould the gel coat was the top coat and was applied as per the advice / instructions from the suppliers. Everything had at least two gel coats.
The one possibility was that the resin used to form the corners was lapped onto gel coat that was more than 48 hours old and hadn't been 'keyed' particularly well and the final gel coat was then put onto fresh resin and more than 48 hours old gel coat.    if that makes any sense 

Im thinking a serious sanding to level things off a bit / remove bubbles and flakes and a lightweight scrim / glass mat layer with a gel coat topping

followed by ..................   eerrrr Ive got a few tubs of black bitumen   

[mespilus]

Isn't GRP normally polyester?

http://www.scottbader.com/global.html