Solar water heating and combi boilers

[Mary Fisher]

Silicone piping.

[PeTe33]

I thought it was a theoretical 230V to fall in line with some European ruling whereas in fact the UK voltage didn't ever change they just factored in a 5% tolerance so 230v +- 5% means that 240v still falls into line.

But I've prolly mis-interpreted something.

How would one tell? Ours is a 1970's model.

[David Hansen]

On Wed, 31 May 2006 15:46:41 GMT someone who may be "Pet @

;¬)" wrote this:-

Before the change it was 240V plus or minus the same amount (can't be bothered to look it up). Now it is 230V plus something or minus less than something. This allows the voltage that arrives at people's house to remain at around 240V, while allowing people to claim harmonisation. IIRC the next stage is to set it at 230V plus or minus something. The voltage will eventually change to 230V, but not as quickly as party politicians claimed.

No idea, I'm not an expert on meter markings. A 1970's model might just run backwards.

[John Rumm]

I was asking about the softness of the water, not the pipes! ;-)

If you go here:

(stick your own postcode "The water supplied to the zone is classified as being moderately hard water, which is river/reservoir derived. As we have a grid system in place whereby we can move water around the Yorkshire region as required, occasionally the hardness of your water may vary."

(Alas the loacl report I looked at omits the hardness figures from the report!)

So the thrust of my question was driven by:

(To quote from

"Water quality

Best practice in water hardness control is more important for direct than for indirect solar water heating systems. Direct solar water heating systems may need robust hardness control: and water softeners may be difficult to install in a few properties. Unless they are plumbed ?indirectly?, water harness control for direct solar is usually achieved by polyphosphates where the water hardness is 100-200 ppm CaCO3 and by the use of an ion exchange softener above this figure. Ion exchange water softeners are thus regarded as essential best practice. Lower cost, but less effective hardness control options such as ?physical water conditioning? may be feasible for indirect solar thermal plumbing."

Hence if you water is "moderately hard":

Which from:

Hardness in mg/l Hardness in mg/l as calcium as calcium carbonate Soft 0 - 20 0 - 50 Moderately soft 20 - 40 50 - 100 Slightly hard 40 - 60 100 - 150 Moderately hard 60 - 80 150 - 200 Hard 80 - 120 200 - 300 Very hard Over 120 Over 300

That suggests a 150 - 200 ppm CaCO3 level, which is in the range that Solartwin recommend you use some form of softening.

[John Rumm]

No, that is about right. It used to be specced at 240V +/- 6%, all that changed was the specified voltage was lowered to 230V and the tollerance widened to allow 240V to meet the spec of 230V -6%/+10%

[Mary Fisher]

Yes dear, but why is there a problem about scaling in silicone piping?

[John Rumm]

Well one presumes that eventually the collector gets blocked with scale or the solar pump stops working, leaving you with a nice roof ornament. You will also get plenty of scale accumulating/forming in the hot water cylinder, and this is free to migrate into the solar system since it is directly plumbed.

Scaling in pipes themselves is usually less of an issue (although micorbore is more at risk) than the rest of the system.

[Peter Parry]

There isn't, there is one in the metal heat collector and metal junction pipes the silicone piping attaches to. If you don't use soft water these quite rapidly become clogged rendering the panel unusable.

[Mary Fisher]

It's not microbore.

The domestic pipes don't block from scale and they're not made from low friction material.

There's lots of room in the cylinder for scale but it tends to stick to the surfaces and not migrate ...

You seem to think you know more about this system than the manufacturers. Do you think they haven't addressed these potential problems?

[Steve Firth]

And they don't work in the same way or at the same temperatures as a solar collector.

The collector is, however the place where fresh water is first heated to a temperature greater than 60C which means that if scale is likely to form anywhere it's within the solar collector. The other problem you have if you have soft water is that you are passing oxygen-rich water through the solar collector and replenishing it before it can become oxygen depleted as happens in domestic hot water systems. This oxygen rich water will increase corrosion.

I do. It's not in their interest to solve such problems.

You fall back on faith that knows much more than any mere newsgroup reader quite often. Do you imagine that everyone who sells some domestic appliance is a genius and that only losers read newsgroups?

[Mary Fisher]

The piping is silicone.

[John Rumm]

'strewth, do you take obtuse lessons?

Never said it was...

Note my comment above: "Scaling in pipes themselves is usually less of an issue". I was highlighting that pipes are not usually the things most affected by scale.

Sorry, I don't think you are paying attention. I am not trying to back you into a corner so that I can say "aha! it won't work then because...", I was just trying to find out more about the system from someone who has actually used it.

I have no knowledge of the system other than what I have read in the manufacturers installation manual.

The *makers say* that in a situation with moderately hard water, hardness control is *required*. Therefore it was my assumption that since you had it professionally fitted following the makers advice you must have some form of water softening device fitted.

I just wanted to know what they used!

Is that such a difficult question?

The makers certainly seem to have addressed the issues in their instructions. Depending on what your installer did, he may have failed to address a potential problem by ignoring the makers advice.

[David Hansen]

On Wed, 31 May 2006 21:48:46 +0100 someone who may be Peter Parry wrote this:-

There isn't any metal in contact with the water in a Solartwin panel. It flows through silicone pipes as part of the freeze tolerant design.

The silicone pipes attach close to the hot water cylinder. Any scale that forms there is going to be little different than they which forms when the cylinder is heated by the coil.

However, taking account of water hardness is advised by the manufacturer. In this case I have no idea whether the installers considered water hardness and decided that it wasn't a great problem, failed to consider it, or were told not to do anything about it.

[Mary Fisher]

I do wonder why you're being so persistent about this. Do you really care about what kind of water heating we have or do you just like baiting me?

That's how you come across.

I doubt that you're considering to install one. I've told you how it works for us, you continue to criticise it.

So why are you bothering?

YOU haven't been listening. I've said lots of times that we fitted it ourselves. Hardness has to be added to our water. That's been said here too and not just by me.

Spouse installed it, with extra advice and encouragement from the makers (I've said that before) because he trusts his own skills, so do I. What you think is irrelevant. We spent months thinking about the system and researching it and others. We are very happy with it, full stop. We have had no problems so far with it. We can't anticipate any problems because it was thoroughly researched (without benefit of your advice, but you can't be on hand or everyone all the time).

So saying, we understand that nothing is perfect. That wouldn't stop us buying a new spoon or car or pc or bag of flour.

Perhaps you live in a world where you are confident that nothing you have will ever let you down. That's not the real world. Stay in it and leave lesser mortals to enjoy or suffer from their own judgements. Nobody's going to blame you.

[Mary Fisher]

Thanks, David.

Spouse installed it. Hardness isn't an issue here.

We don't have softeners, they're not needed and are undesirable. No water - hot or cold - appliance suffers from scaling over normal periods of use (e.g. twenty + years for a multipoint water heater, 22 years for a central heating boiler, a hundred years for a copper kettle ... ).

Mary

[David Hansen]

On Thu, 1 Jun 2006 09:59:32 +0100 someone who may be "Mary Fisher" wrote this:-

Sorry. I had forgotten that you have said that several times. It's probably because I'm of the male persuasion:-)

I think that those who perhaps mainly have experience of hard water areas tend to not appreciate what soft water is like. People sometimes wonder why I don't use the water softener in my dishwasher. The reason I don't is that it makes the water far too soft.

[Peter Parry]

"How hardness affects Solartwin

Is hardness control required? Yes. It is very important our panels heat up to over 60C. High temperatures promote limescale deposition. Limescale could eventually block panels unless controlled...Warranty is invalid for incorrect hardness methods or thresholds... For direct installations, use nothing else except: ? Polyphosphate 100-199 ppm CaCO3 only ? Ion Exchange Water Softener 100 ppm CaCO3 and above"

[Peter Parry]

Of course they have - they require the hardness of the water to be controlled.

"0-99 (max) ppm CaCO3 very soft. No water hardness treatment to be done here.

100-199 (max) ppm CaCO3 slightly hard-mod hard. EITHER Fernox Superconc. Preventer OR Ion exch water softener req'd

If EVER over 200 ppm CaCO3 hard-very hard. Ion exchange water softener required"

[Mary Fisher]

I think, to be fair, that the same applies to people who mainly have experience of soft water. When we visit a son in Wiltshire I'm amazed at the scale on everything touched by water.

Yes, even him :-)

But when we visit a daughter in Wales, whose water is from a spring, we're surprised that it's even softer than ours.

It certainly made a difference when the water board put hardness in (for the sake of our arteries).

We've never tried it.

Mary

[John Rumm]

Yup I have nothing better to do....

I asked a question that is all. I can't help it if you have to be so defensive about it. This is obviously a "touchy" subject for you, why I am not sure, perhaps you expect everyone will challenge your decision to install it. Not me.

I appreciate you enjoy arguing for the sake of it, but sometimes, just sometimes you could just answer a straight question.

So to recap in this thread: I have asked about your system, what components it consisted of, what it cost, what water softening was installed. Back on topic I have also discussed solutions for combining solar with a combi, then had a diversion into back feeding AC power supplies. Mostly you have given in response suspicion, and avoidance. Did the earth move for you too?

OK I give up, I don't want to know *that* much. Happy now?

Then my presentation or your perception is flawed.

I am not considering installing one for me, since it would be incompatible with my system. That does not mean that I don't want to understand the system, its benefits, and pitfalls, and hence form an opinion as to whether it would be appropriate for others who *may* want such a system and might ask me to install it.

Now, show me where I have criticised your system.

So I can find out more. Questions do not indicate hostility. You need to address your preconceptions.

OK fair enough. You have said that. The difficulty is that the small fragments of information that you did give have been handed out piecemeal and obfuscated by the additional twittering.

I am sure he did his bit just fine. What I was trying to reconcile was the conflicting advice - the instructions say use water softening, yet it seems they did not suggest that you should. This may mean that someone screwed up, it may be they think they can sell more systems this way, it may be your water is not actually hard enough to be a problem, it may be the advice in the instructions is wrong. Who knows? You probably do, but it seems you don't want to say.

I would not be qualified to offer you advice in these circumstances, and so I would not.

Again you are being defensive. I was not criticising your purchase. The only "criticism" I have expressed if you wish to call it that, was the statement that the type of system you have would be of little use to the owner of a water heating system that is based on a combi and has no storage. Personally I don't consider that a criticism.

Yes that would be nice, but I am not *that* delusional.