solar; thermostatic valve

Ging Ging

Hi I did the solar hot water course last year and was told a thermostatic mixer on the hot water coming out of the storage tank was required(to prevent scalding). I've worked on a couple of jobs since where we always fitted a one.
Now I'm with a new company and they aren't planning to use thermostatic valve at all , and Im to go along and fit systems regardless. I'v pointed out the section in the REA training manual but it only refers to a draft European Standard ENTC 312 part5 not any working legislation requiring them. Cant find anymore info on this standard????
Iv also checked online but all the info I found says its "best practice" not legal requirment, which isnt enough to get a thrifty plumber on a price to splash out for the valve.
Even the SEI grant form has a section to mark yes or no as to wether its been fitted (still a bit ambiguous). Although Iv heard anecdotely their inspectors want them fitted. Anyway these are new houses so no grant forms to be filled in.
They're not supplied as standard with the solar kits or cylinders A major supplier is saying they are optional extra, another told me that the plumbers just wont pay for them because they dont have to.
If I was buying the material Id be fitting them but I'm only the spanner monkey. Can anyone tell me are they required or can you fit a system without them? I know it will work but I mean is there anything out there in Irish standards or regs? This seems to be the poor relation of the safety features.

quentingargan

Ging Ging wrote: »

Hi I did the solar hot water course last year and was told a thermostatic mixer on the hot water coming out of the storage tank was required(to prevent scalding). I've worked on a couple of jobs since where we always fitted a one.
Now I'm with a new company and they aren't planning to use thermostatic valve at all , and Im to go along and fit systems regardless. I'v pointed out the section in the REA training manual but it only refers to a draft European Standard ENTC 312 part5 not any working legislation requiring them. Cant find anymore info on this standard????
Iv also checked online but all the info I found says its "best practice" not legal requirment, which isnt enough to get a thrifty plumber on a price to splash out for the valve.
Even the SEI grant form has a section to mark yes or no as to wether its been fitted (still a bit ambiguous). Although Iv heard anecdotely their inspectors want them fitted. Anyway these are new houses so no grant forms to be filled in.
They're not supplied as standard with the solar kits or cylinders A major supplier is saying they are optional extra, another told me that the plumbers just wont pay for them because they dont have to.
If I was buying the material Id be fitting them but I'm only the spanner monkey. Can anyone tell me are they required or can you fit a system without them? I know it will work but I mean is there anything out there in Irish standards or regs? This seems to be the poor relation of the safety features.

The gaffer's right - they aren't mandatory, but you're quite right - they should be. There are a number of reasons for including them;
1) Any failure of a thermostat will cause scalding
2) If you fit a mixing valve, you can set the cylinder to go up to 80 or 85 degrees (provided it isn't a hard water area). This can maximise the storage of hot water during periods of extended sunshine - 200L at 85 degrees is as much stored as 300L at 60 degrees.
3) I assume your skinflint boss won't let you use a heat dump either. If you allow the cylinder to go to 85 degrees, at least the system won't go into stagnation as often (though again, heat dumps are best practice, and prevent degradation of glycol and stresses on compression system which are the number one cause of system failure).

If you like working to better standards, pm me - hate to see your talent wasted...

MickLimk

I completely agree that they should be mandatory for all the safety reasons and benefits that Quentin has mentioned.

However, TMVs can have their own issues. The minimum pressure usually required for a TMV is 0.2 bar. A lot of houses in this country will not have 2 metres head between the hot water cylinder and cold water tank in the attic. In these cases a TMV will not work or else reduce the hot water flow to a trickle even with a separate dedicated cold feed.

In the situation where one has been installed and correctly oversized to deal with the pressure reduction but the home owner doesn't like the fact that there is a slight decrease in the hot water pressure, what can you do!?

I'm not trying to make excuses for not installing them, as I said at the start, I think they should be mandatory.

PeteHeat

Hi GingGing,

Last persons hand on the system is the one responsible, that's an old rule used by the legal profession when looking for someone to blame.

There are a lot of details referred to as "Best Practice" which are followed because that is what they are, I agree the valve is easy to install when fitting the system so why not ?

If the customer / end user knew how little it cost to save themselves or their children from being scalded they would have every right to be annoyed.

The fact that the valve needs a reasonable head of pressure should be established when designing the system and changes should be made during installation.

Some might say they would lose the job if they build in the extra cost of ensuring the valve works, I say tell the customer why the extra work / cost is necessary some may delay installing the system until they can afford to have it done properly others may decide on taking the cheapest option.

I think you would be surprised at how many consumers will opt for the better job.

Ging Ging

Well thanks for that lads, at least I know now. Irish regs lagg behind again!! BOoo! I'll continue to voice my dissapproval but to be honest I can't see me getting anywhere. :mad:

I'll also air on side of caution as regards pressure reduction. Have a gravity pressure nixer (non solar) coming up, for a customer who got scalded by a faulty shower valve but doesnt want to change shower:rolleyes: I've suggested fitting a master thermostatic valve and they're thinking about it. Depends how much you like your skin I suppose!

AckwelFoley

Tell the arse's you work for that they can buy them for about €45 and trust me - it will come back to bite them if they dont.