Unvented cylinders DIY installation

[Tim Downie]

Anyone in Scotland installed their own?

Looking at

't seem to include any words indicating that it *must* be installed professionally.

From section 4.9.1 [quote] Competence of installers

This might include current membership of a registration scheme operated by a recognised professional body. This could include those administered by the Scottish and Northern Ireland Plumbing Employers Federation (SNIPEF) and the Construction Industry Training Board (CITB) or an equivalent body.

The following points should be noted in relation to installation of an unvented hot water storage system:

. the installer should be a competent person and, on completion, the labelling of the installation should identify the installer;

. the installed system should be meet the recommendations of BS 7206:

1990 or be the subject of an approval by a notified body and incorporate

the safety devices outlined in clause 4.9.2 ;

. certification of the unit or package should be recorded by permanent marking and a warning label which should be visible after installation. A comprehensive installation/user manual should be supplied;

. the tundish and discharge pipework should be correctly located and fitted by the installer and the final discharge point should be visible and safely positioned where there is no risk from hot water discharge.

The operation of the system under discharge conditions should be tested [/quote]

Leaving aside the advisability of DIY installation, is there anything that actually precludes a DIY installation by a competant person?

Tim

[Doctor Drivel]

G3:

"Requirement G3 does not apply to -

(a) a hot water storage system that has a storage vessel with a capacity of 15 litres or less;

(b) a system providing space heating only;

(c) a system which heats or stores water for the purposes only of an industrial process."

Your link was non-domestci.

[Tim Downie]

True. Here's the right link (for Scotland).

the same thing though so it would seem that DIY is theoretically possible.

Tim

[Alan Braggins]

Interesting potential loophole in that it doesn't say has _only_ a storage vessel with a capacity of 15 litres of less.....

[Doctor Drivel]

> Says the same thing though so it would seem that DIY is theoretically > possible.

Another document clearly states DIY is out.

[Tim Downie]

>>> Says the same thing though so it would seem that DIY is theoretically >> possible.

Where?

You've said it's possible with BCO checking in another post. You seem a bit confused.

Tim

[Doctor Drivel]

>>>>> Says the same thing though so it would seem that DIY is theoretically >>> possible.

That is not DIY as such. You pay for the BCO, which is not cheap. Many BCO's do not do it and farm it out to an approved man, as they do with Part P in electric. You may as well pipe up the cylinder, and remove it. Then get an approved man to connect, fill and test. I see no reason why a DIYer can't do the lot as long as it is not filled up with water, then get an approved man to fill and test and sign off.

[Tim Downie]

Is that the sound of backpedalling I hear?

Tim

[Doctor Drivel]

Not at all. You can install it with BCO approval, if he decides he wants to take it on. You can install it all and leave it dry and have an approved man check, fill, test and sign off. Either way it is not DIY as in installing a gas boiler, as a professional is involved with the unvented cylinder installation.

You clearly cannot service any part of the cylinder as a DIYer and they need one every year. They are a waste of expensive time, use a vented heat bank, far, far better and does the CH too and can be DIYed and no expensive annual service.

[Tim Downie]

I think you're the only one who can't hear it.

So you keep saying but won't provide any evidence that this has to be done by a professional

Vented heat bank may not be suitable if your boiler is in your loft.

Tim

[Doctor Drivel]

It is there so look!!!!! Find it yourself - cheeky sod!. You brought up the topic. You have been gioven some linsk so get the rest.

Then stick that in the loft too. Or you can also heat the heat bank via a coil or preferably a plate heat exchanger to heat the cylinder top-down, solving that problem.

Ask don't go on as it you know it all - which you clearly do not.

[David Hansen]

On Wed, 25 Feb 2009 16:00:47 -0000 someone who may be "Tim Downie" wrote this:-

I tend to the view that someone who puts a boiler in a loft deserves everything they get. Boilers are best placed where the heat they give off, which will never be zero, does something useful before it leaves the building.

[Ed Sirett]

Are you think that if you install half a dozen 15 litre units in parallel then you can get around the rules 8-).

The intention of the rule is to separate out the smaller unvented cylinders usually electrically heated and intended for single point usage.

[Doctor Drivel]

He can fit a number of 15 litre units and DIY it. But why, when he can fit a vented heat bank and DIY that.

[Alan Braggins]

_As worded_ it would appear you could fit a 15 litre unit and a 300 litre unit, and the result would be a system that has a storage vessel with a capacity of 15 litres or less. That doesn't make it a good idea.

But tell me more about the servicing requirements. When Nu-Heat replaced my failed vented heat bank with an unvented one because they didn't do vented ones any more, no servicing requirement was mentioned.

[Tim Downie]

I've not seen any info pertaining to a legal requirement for an annual professional inspection so far. If you can't point to them or find them just say so.

I know I could use an indirect thermal store or other system but the thread was about DIYing unvented cylinders, not a platform for you to parrot on about thermal stores & heat banks.

Tim

[Tim Downie]

I wouldn't disagree but when our boiler was installed, house extensions at the time meant that options were very limited without getting into some expensive flu options & condensate pumps etc.

Tim

[Doctor Drivel]

????? Fit 300 litre and is less than 15 litre? Wow! Tardus in reverse.

______________ G3 SECTION 3 SYSTEMS UP TO 500 LITRES AND 45 kW

Where unvented hot water storage systems means an unvented vessel for either :

a. storing domestic hot water for subsequent use; or

b. heating domestic water that passes through an integral pipe or coil (eg water jacketed tube heater/combi boiler)

and fitted with safety devices to prevent water temperatures exceeding 100º C and other applicable operating devices to control primary flow, prevent backflow, control working pressure and accommodate expansion. " _____________

So, b)

b. heating domestic water that passes through an integral pipe or coil (eg water jacketed tube heater/combi boiler)

So, an unvented vessel that heats DHW passing through an integral pipe or coil, which can be either a water jacketed tube heater (a normal integral DHW coil) or combi boiler.

I think the "combi boiler" means the plate heat exchanger needs an unvented ticket. But says "integral". A combi cannot be integral.

Combi boilers and multi-points can be used to heat DHW in unvented cylinders using a brass pump for circulation.

It omits immersion heaters - they don't have water passing through coils.

Nu-Heat Look at the presurised thermal store (heat bank really):

says: "No G3 building regulations approval required, the unit can be fitted by any competent installer". So, it can be DIYed.

a) If a pressurised thermal store (integral DHW coil), then G3 applies b) If a pressurised hrat bank (using aplate heat exchnager), then G3 does not apply.

Nu-Heat use a plate heat exchanger, not an ingeral coil, so no G3.

Have a look here -

states this -

Requirement G3 does not apply to -

(a) a hot water storage system that has a storage vessel with a capacity of

15 litres or less;

(b) a system providing space heating only;

(c) a system which heats or stores water for the purposes only of an industrial process.

Now....

Nu-heat, the makers of the thermal store say a pressurised thermal store does not require an unvented ticket to install, as the DHW content in the plate heat exchanger is not an integral coil. That is correct. The boiler, cylinder and heating circuit are all the same water pressurised to 1 bar (cold) - heated from cold the pressure never gets above 2 bar inside the cylinder. They operate on far less pressures than the vast majority of unvented cylinders. An unvented cylinder requires a pressure relief valve on the cylinder and a high temperature relief valve off the cylinder too.

A pressurised thermal store requires only one pressure relief valve between the boiler and cylinder, as per normal sealed systems - they are set to 3.5 bar. In effect the pressurised cylinder is regarded as a bigger pipe in the system. The cylidners come with one and there is one on the boiler, so two on the system. I personally would put two pressure relief valves on or near the cylinder with two separate pipes as one pipe might get blocked for some reason - just in case, so three in all. They are cheap. No tundish is needed. A high-limt temperature cut off stat on the cylidner would be a good idea too.

The 210 litre pressurised store takes a 24 litre expansion vessel which copes with the boiler, cylinder and CH circuit.

Got it? If I was you, I would put an extra pressure relief valve on a pipe very near to the top of your cylinder - just to be sure.

[Doctor Drivel]

Heat banks a near zero-risk and superior all around. Only fools fit unvented cylidners. I see which one you are.

[Tim Downie]

*yawn*

Still can't answer the question about annual certification I see.

TIm