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

[desperate]

Noel said

How come we can always bleed air out of that high level rad thats always left on ?
How long has it been dissolved in the circulating water ?
Why has it not oxidised the unprotected insides of the steel rads, at least the upper part of the rad that has the air build up ?
Where do steel radiators tend to form pin holes ?

Cos you probly have air leaking into the system somewhere.
Not long
It does, thats why you can wash a whole load of black gloop out of a used rad.
At the bottom where the copper swarf tends to settle

Quote
Am I focusing too much on pH balance and ignoring other aspects of chemistry ?

I dont really know how important the pH on its own is, but I do know there are loads of causes of corrosion in heating systems ususally involving air entrapment. I also reckon that unless you can eliminate the cause, just pouring in various inhibitors is a waste of money.
If you take a sample of the water in your pit and let it stand in an open glass, do you see bubbles forming on the side of the container? if you do I think this may have some significance. But I also feel as others do that you have some electrolytic action going on there. I am not sure what the answer to that is.
Desperate

[TwoHorsePower]

Frotter/Stuart - seemingly there's a brand of tree stump remover that's largely potassium nitrate.
Or has anyone tried making their own salt petre by peeing regularly into a brick-walled compost/manure heap and scavenging the efflorescence? You could run a heat exchanger through the heap so you can claim you're capturing energy from waste?

...sorry for going off topic Noel & keep up the good work!

[noelsquibb]

Hey THP

I have been known to pee against brick walls and I know a site where they've got a lot of efflorescence on the brickwork..... sounds like a novel way to fell trees.



Desp.

I reckon you are better informed than you try to make out.
Pinholes from copper swarf at the bottom of steel rads will be the same chemistry I reckon.

Took some pictures in the snow today . These demonstrate where I am loosing a little heat from the top of the heatstore.
The melt is pretty much where the expanding foam has been peeled off the underside of the cellotex lid and where the pipes rise out of the ground to enter / leave the heatstore. Considering all the circuits are getting regular or constant hot water flowing through, this amount of melt is acceptable.

The solar header shows no melt on the outer skin or the insulated and plastic protected connecting pipes above the slates and I am pumping hot water through continuously while its so cold.

[noelsquibb]

now the reason I didnt stay in the shed today and play with the chemistry set is because I was having too much fun.

sorry 

[noelsquibb]

Is it magnetic? can you dissolve it in acid(try brick acid, I know you love that stuff)? will it dissolve in caustic soda? can you melt it with a lighter? blowlamp? oxy- acetylene? Does it smell when hot? 
I'm thinking it may be magnetite Iron oxide?

I did manage to do some tests on the shiny scum today.

Its not really magnetic although there is some attraction. more like static than magnetic though.

It will melt. I used a fine steel grille and a blow torch from above.  Too close and the flame blows the particles away.
It seems to re-solidify to give the same shiny black appearance. No smell but with such small amounts involved, I could be missing something.

It dissolves in brick acid, first going a dirty brown then a golden yellow.

So does that confirm magnetite iron oxide and what can I conclude from knowing this ?

A thought struck me regarding the sacrificial anode and its lack of shininess.
Some of the washings in the mine settling ponds have shown up to 18% zinc with plenty of lead and iron, a splash of copper and trace amounts of cadmium and arsenic. All ground up nice and small too.

What harm could a couple of kilos of this material do?
Big surface areas and all sacrificial, take your pick, gravy.
Its only got to last till spring. 

[desperate]

Hi Noel
Now just stop messing about on them motybikes and get back on the pit o doom, damn filthy bikers

Anyways I been thinking about this chemistry set you been growing in the garden, dont take this too literally as although I do know a bit about chemistry, I sure aint no expert.

 Gut feeling is that you are making black Fe3O4 which is created in oxidizing conditions where there is not an abundance of free oxygen. I am pretty sure if you dissolve this stuff in Hydrochloric acid it would produce Ferric Chloride which is deep yellow in crystaline form The above is kind of normal chemistry that will occur in rads untill the oxygen runs out, I think your heatstore probably has a large enough surface area to replenish the oxygen content, Is there any splashing on the surface as the return flow enters the store?
I think you also have some electrochemistry going on as evidenced by the smell, that is why I was hoping we could collect a sample of the gas that is dissolved in the water, and see if it was Hydrogen.
I think the only way to completely cure any electrlysis occuring is to electrically isolate any different metals in the system, which I think is pretty much impossible or to constuct the heat ex out of either one metal IE copper or metals that have the same electrovalence? or reactivity? ( help my brain is fading). You could stick a sacrificial anode in the pit, but it is a bit tricky to know exactly what to connect it to, and as its name suggests it will dissappear after a while, and as it dissolves so it will load the water with yet more unwanted ions to go bonkers somewhere else.

I am still thinking, but the fuse has gone pop up there for the moment.

Desperate

[noelsquibb]

Gut feeling is that you are making black Fe3O4 which is created in oxidizing conditions where there is not an abundance of free oxygen. I am pretty sure if you dissolve this stuff in Hydrochloric acid it would produce Ferric Chloride which is deep yellow in crystalline form  The above is kind of normal chemistry that will occur in rads until the oxygen runs out, I think your heatstore probably has a large enough surface area to replenish the oxygen content, Is there any splashing on the surface as the return flow enters the store?
I think you also have some electrochemistry going on as evidenced by the smell, that is why I was hoping we could collect a sample of the gas that is dissolved in the water, and see if it was Hydrogen.
I think the only way to completely cure any electrolysis occurring is to electrically isolate any different metals in the system, which I think is pretty much impossible or to construct the heat ex out of either one metal IE copper or metals that have the same electrovalence?

Desp

Your assessment seems to fit the observations and I reckon we agree that using only copper in the pit is the best way to deal with the electrolysis.

Do I have a hydrogen hazard though ?
I guess that with it being keen to float up and the lid not being airtight we are not likely to have a buildup.
Connecting the little fuel pump to the battery, to drain the insulation, could ignite any flamable gas though.
How to collect a sample ?  Suppose I could draw from just above the water and bag it ?
Don't have a gas-chromatograph (?)  lying around though.


I mentioned the general gravy pit problem to my mate Jim ( ex Camborne Sch of Mines ) and he immediately reckoned it was to do with chlorides in the tap water. - He didn't have time to elaborate as he was meant to be working, not trying to locate frozen water features to go ice climbing -
He agreed that all the oxygen needs to be removed from the water, agreed with the oil slick seal and a lump of pure zinc in the gravy connected to the pipework.

I am with you on the zinc and accept that there will be a 'cascade' of chemical reactions with each metal adding to the potential for 'unwanted ions to go bonkers'.

As for splashing in the gravy pit ? no, no, no, the gravy is quite static and stratified, the moving water is all contained inside heat exchanger circuits.

I promise I will do the schematics soon.




Meanwhile further expansion of the envelope occurred yesterday -

I ran the oil combi a bit longer than I really needed to ( cos it does keep the radiators warmer than circulating the CH through the heatstore ) and at the same time the fire was being driven fairly hard, mainly to get the lounge warmer, I suspect.

Net result -  the lowest temp in the heatstore was 70c and the highest 79.5c. That's a cool 10c higher than its normal temp range.   

This prompted me to stop the combi and run the CH water through the heatstore with 4 radiators open ( usually 2) and have a jolly hot deep bath ( with top ups )

1400 litres avg temp 75c, incoming cold main 2c, how much oil have I saved ?  Plenty. Don't care really. 

The system seemed to be quite happy with this additional temperature but I am not keen to push any further.

Never been so warm

noel

[desperate]

Noel said

1400 litres avg temp 75c, incoming cold main 2c, how much oil have I saved ?  Plenty. Don't care really.

The system seemed to be quite happy with this additional temperature but I am not keen to push any further.

Never been so warm

The system sure is a goodun, once we get these niggling little problems sorted. They told me at business skool that "failure is learning" and "fail forward" and other assorted ballaeux in which case I must be a jeaneus

If I ever get to build my dream house it would incorporate a system not dissimilar to yours(interseasonal store sort of thing) so I have a vested interest, Chlorides in the tap water eh? hmm books out time again.

Desp

[noelsquibb]

Ran out of dry wood a few days ago and came home to find a couple of bags of coal ( at £8 a bag   )
Ok it worked but because the fire was sat a lot lower in the firebox we didn't seem to get as much heat into the boilers even with the coal glowing nicely.

Obviously the woodwarm fire works better with wood  

So my emergency dry wood has been broken into - an ash tree thats been dead for a few years but stayed upright.
Ironic to have a big stack of wood by the logshed and have to go tree harvesting though.



Had a thought regarding a possible way of balancing the chemistry in the gravy pit a bit.
Not so much about pH balance or inhibitors but what about balancing the electrical flow.

I am getting a reading of 0.5 volts between the gravy and the plumbing so  ........

Can I put in a similar voltage and REVERSE the electrolytic shenanigans thus depositing iron and copper back on the depleted surfaces ?and if I can how would I do this  in a 'failing forward' kind of way


noel

[daftlad]

Noel,
I had epifeny epithe... erm eppidem ah.... moment of clarity the other night.
Right what is the difference between the pit o gravy and a normal open vented thermal store?.... well not much.
There is more of a chance of oxygen getting into the water than a normal thermal store, but oxygen can still get into an open vented thermal store through the expansion and contraction into the header tank.
AND
your tank is outside the equipotential zone, it is at true earth potential rather than the earth potential provided by the leccy board.
So your pipes going to the pit are at leccy board earth potential (because they are bonded) and the water is at true earth.
What  will might help? erm well The leccy board earth needs to be dragged down to true earth, to do this run a 10mm earth wire from the MET (main earth termainal (at the fuse board)) to the ground next to the pit o gravy and put some earth rods in maybe knock 3 in around the pit? (some copper pipe will do if your ground is soft enough) and also bond the earth wire to all of the pipes feeding the pit o gravy.
In other words connect everything together electrically including the earth.
I might be talking rubbish but I am sure one of the forum members, one of the ones with the big brain, will correct me if I am.
ta ta

[noelsquibb]

Hey Daftlad

what a great thought and thank you for even thinking it.

What might spoil the idea is the fact that living out in stickland we do not get any of that PME that most folk get, AFIK.

In fact we seem to rely on,  err ,  a 10mm earth wire from the MET (main earth terminal (at the fuse board)) to the ground next to the pit o gravy where the main earth rod is buried ( there are a couple others located outside remote buildings that are fed from the same supply so are interlinked )
I could easily put a few more bits of copper in the backfill around the gravy pit and create a more direct bonding link though.
Deffo worth a try. Hopefully 2.5 sq mm copper wire will be up to carrying the potential load of 0.5 volts, current currently unknown.

I agree that other vented thermal stores ought to have similar chemistry as they have the the same ingredients and function.

Internet research suggests that stainless steel, glass liners or specialist cement based liners are the solution for commercially available vented stores with copper for heat exchangers. So others have had the problem and found expensive but reliable solutions.
I accept that the mark two heat exchange array will contain only copper and solder and the mods will have to be done at the earliest opportunity after the next pin hole opens up. The idea of reversing the potential was only as a stopgap, to try and keep the iron rads intact till the weather gets warmer and the lawn gets drier .....

I was wondering if stuffing leccy in the opposite direction to reverse the metal removal was even possible ?
Don't think lectrons behave like water and go where directed though.

Does the big brain get passed around ? If it does, what do I have to do to have a go ?

noel

[wesnet]

Noel your idea of applying a reverse voltage is what is or was used for cathodic protection of ships. Have a look at this document it may be of some help http://www.bushman.cc/pdf/corrosion_theory.pdf

John

[KLD]

Yeap, check Wikipedia for "Impressed current cathodic protection (ICCP)".
Sounds like it's usually only applied to large structures.

Whatever happened to your sacrificial anode? Did that get thrown into the gravy? Hope you've connected it electrically to the other metallic parts?

Klaus

[noelsquibb]

John,

Thank You.
That's an excellent doc. Seems to fit the bill perfectly.
I can pretty much understand it and it confirms that my daft idea is already in regular use.
I will try to measure current and work out a way of delivering a suitable balancing flow.


Klaus,

Further confirmation of what I just read in Johns doc. Thanks

The sacrificial anode, that consists of random bike bits, is still in the gravy and it is connected to the circuit with the steel radiators. Previous inspections suggested not much was happening to the surfaces of the anode.
I haven't looked at it for about 3 weeks because its been jolly cold and I have only lifted the cover enough to top up the water level.
Will be doing a routine pump out and top up this weekend, so will inspect.



Had a complaint that there was a 'smell of oil ' near the pit. 
Heh, that's not oil, that's my chemistry set.
Easier to blame the semi redundant oil combi though 

Heavily scented pot plant required I suspect.

noel


 

[KLD]

"Heavily scented pot plant required I suspect."

Well, if you take the top insulation boards away and cover the whole lot in a poly tunnel, you could have a  few nice fragrent tropical plants 

Klaus