Megaflow unvented pressurised 125 litre hot water cylinder query???

[kean]

Hi a plumber has recently installed a DD125 MEGAFLOW hot water cylinder into my 4th floor flat, however it was not possible to connect the safety outlet to the outside due to the original one not having this (Gledhill). At the moment i have put a bucket under it. How much of a problem is this? i understand the safety valve is to relieve the pressure on the input?.

 

[nysk2008]

are you talking about the discharge from the pressure relief valve? If so, its a big problem

 

[kean]

yes i think its the pressure relief valve. have i bee mugged off? Is the solution to install a pipe from that which leads to the outside?

It seems to be working fine now..no discharge from this pipe.

 

[Plumbstar Tom]

my solution is ring megaflow as you dont want this hanging over your head if its wrong

 

[kean]

I mean it will still release water (into the bucket) if there is a problem so overpressure is not a problem? i guess flooding is a possibilty should a problem occur.

thoughts?

 

[bob the plumber]

lol, if you cant take it safely outside why dont you run it into the nearest waste pipe via a hep trap...its allowed, im sure it will even suggest it in the manual. Just make sure your d1 and d2 pipes are up to scratch

 

[Plumbstar Tom]

im sure into a bucket is not regs

its very hot water, as it needs a TMV to cool it before it is used

 

[fagsanbooz]

Hi a plumber has recently installed a DD125 MEGAFLOW hot water cylinder into my 4th floor flat, however it was not possible to connect the safety outlet to the outside due to the original one not having this (Gledhill). At the moment i have put a bucket under it. How much of a problem is this? i understand the safety valve is to relieve the pressure on the input?.

It's there as a safety valve in case of 'pressure' in system increases to a certain point or if coming from cylinder 'temperature' exceeds a certain amount. It should be taken to a tundish, then to a pipe that takes it to a safe place outside. As 'bob siad, building regs now permit the installation of a discharge to an internal soil stack via a waste pipe. The installer should have done either of these if he/she held the qualification and understood how an unvented system is designed to operate. The fact they have not means they did not install it correctly or to regs. get them back to complete, if they won't, contact your local council building control for advice.

 

[GQuigley67]

i came across this the other week, undersink water heater PRV was discharging into a plastic cup, fitted a tundish and tee'd it into sink waste.

 

[plumber0808]

i dont know how people can do work like that and then just walk out the door and carry on as if its normal

 

[ecowarm]

if something went wrong and your 125lts of water heated to 100c and turn to steam at 100c you would have aproximatly 212500lts of steam ,,,,,,,,, will the bucket hold that?

 

[plumber0808]

it will hold 15 litres of the 212500 litres
lol, after that you better get your skates on

 

[bob the plumber]

im sure into a bucket is not regs

its very hot water, as it needs a TMV to cool it before it is used

Thermostatic mixing valve Tom??? I believe your probably thinking thermal store hot water supply?? You dont have a TMV on the outlet of a Tempreture Pressure Relief Valve on an Unvented Cyl, you should have non restricted flow to termination point which should be at a low level or discharged into a waste safely

 

[bob the plumber]

i think your installer should be shot Your tempreture pressure relief valve will kick in as a last resort if your cylinder overheats to 90-95c, if it does it will release the water (HOT) into the bucket, if the bucket isnt big enough you will get a wet floor or the person who lives below you may get a wet living room ceiling Having paid for the job which i assume you have i would imagine that you would like it to be done properly so just ask him back, if he doesnt want to come back just refer to my opening statement

 

[Howsie]

My understanding of the regulations is that it must vent to outside via D2. When did the regs change to allow D2 into a stack?

 

[Reg Man]

Sounds like you have been done. Its as everyone else has said, Discharge to outside terminating in a safe location. On certain circumstances the local authority will allow you to have the discharge into the waste system via a waste trap, as long as the discharge is visible. Which brings another point to the front. Stored unvented hot water system's require building regulations compliance, wether new or replacement. So once compliance has been met you should have a local authority certificate to show that its been passed by building control. Alternatively you use an installer who has prooved competance and is registered with a goverment approved competent person scheme. These members can self certificate the work through the scheme and a certificate is issued. If you do not have a certificate the installation has been carried out illegally.

 

[kean]

when you say safe location what do you mean. He suggested plumbing a pipe to the exterior wall but i would have to get the freeholders permission to do that (its a block of flats), this would then drop water onto an outdoor tiled landing by the front door, where there is a drain for rain water etc.. would that be ok?

 

[nysk2008]

Hi there,

If youre in a block of flats its more than acceptable to terminate the discharge from a Pressure/Expansion Relief Valve into a stack therefore not needing to run it down the wall etc. Like the guys and girls say though there are a few rules.

1) Tundish must be fitted and visible
2) the pipe connected to the bottom of the tundish (D2) (probs 22mm) needs 300mm min to the first bend
3) Probably some others but cant remember right now

At work we terminate into fanny trap (dry trap) which in turn goes to 1 1/4 pipe to the stack.

Long and short of it, get the cowboy back and get it sorted.

Ta

 

[kean]

Yes he's coming back on tuesday to connect it to the soil stack. He is gas safe certified (checked his registration number) so this means he can self certify his work. Do i need to let the building control know myself though?
What is a tundish?

 

[nysk2008]

to the best of my knowledge just because he is gas safe it doesnt mean he can comission Unvented hot water storage cylinders however i'd assume he is more than capable to install, will have to check the self certification though. I've put a pick of a tundish which i hope you can see, they dont all look like this but are much of a muchness.

 

[mboshier]

got a picture? that is crazy!

 

[bob the plumber]

being gas registered doesnt mean your installer is qualified to install an unvented. To be able to do so you should hold your unvented g3 ticket

 

[GQuigley67]

i have unvented on my card now

 

[kirkgas]

I mean it will still release water (into the bucket) if there is a problem so overpressure is not a problem? i guess flooding is a possibilty should a problem occur.

thoughts?

you are right it will release excess pressure, or excess pressure caused by excess temperature, into the bucket, but if it does it is very unlikely that it will only discharge a small amount and not overflow the bucket and flood the 3 flats below you, this needs to be attended to ASAP, excess pressure can happen at any time and when properly fitted will discharge safely to outside or properly into a drain, check the MI for your tank, it will show you a hep2o valve, which can be fitted to the soil stack, then phone a qualified guy to check out the work done, cause if they have left this then i would suggest that the rest of the work was checked and this fault rectified

 

[kirkgas]

im sure into a bucket is not regs

its very hot water, as it needs a TMV to cool it before it is used

which unvented tank require a TMV to be fitted?