Blending valve combi to increase flow?

[Aire]

Don't know if any of you have watched PB's latest YouTube vid. He installs an atag combi and straight from the hot water outlet, he fit a TMV, now I can only presume this is to increase flow rate of the hot water.
Correct me if I'm wrong, but isn't using a tmv in this way wrong? The use of tmvs is for the vulnerable right and should be installed if the risk of scalding is greater than the risk of legionella, so PB's use of the valve is incorrect as he is creating an unnecessary breading ground for legionella. Is there any regs against this or is it just not best practice?

 

[ShaunCorbs]

depends what temp its set at, if its 60 your fine if lower bit naughty as its connected to the water mains it comes under there ruling for legionellas

 

[Aire]

depends what temp its set at, if its 60 your fine if lower bit naughty as its connected to the water mains it comes under there ruling for legionellas

He set it to 50°, I suppose any higher and it would be ineffective as the water temp won't leave the boiler any higher.

 

[ShaunCorbs]

Huston we have a problem then

 

[chris watkins]

• Hot water storage cylinders (calorifiers) should store water at 60°C or higher
• Hot water should be distributed at 50°C or higher (thermostatic mixer valves need to be fitted as close as possible to outlets, where a scald risk is identified).
• Cold water should be stored and distributed below 20°C.

above is from the HSE website "Managing legionella in hot and cold water systems"
Blending valve installed to manage the risk of scalding such as those required to be installed on every new bath installed under Part G should be fitted as close as reasonable practical to the fitting (point of use).
Blending valves used to protect against over temp in solar or primary stores (thermal limiting valves) & the like are set to 60/65 degC.

Managing legionella in hot and cold water systems

Provides links to sources of information and guidance on health and safety in the health and social care services sector.

www.hse.gov.uk

 

[Aire]

Huston we have a problem then

I thought it was wrong, I thought that if it was as simple as fitting blending valves to increase the flow rate then all manufacturers would be doing it.

 

[Millsy 82]

I honestly think that people like that fit these unnecessary things just purely so they can say I fit this and that etc.

It's like the deaerator thingy (never saw one until matchless put a picture up so I google them) on a sealed system what the hell do you need a deaerator for?

It's all just so they can justify charging £800-900 just for a combi swap.

 

[Mastermixlee]

Saw that video and in my head it makes no sense whatsoever as its just reducing the max outlet temperature and not increasing the flow rate any more than just running a bit of cold at the same time (which would achieve the same goal... If anything have even better flow rates as the connections to the taps themselves are often the biggest restriction in flow rate).

 

[king of pipes]

Load of rubbish it won't make the slightest bit of difference on flow rate. Kop

 

[Harvest Fields]

I honestly think that people like that fit these unnecessary things just purely so they can say I fit this and that etc.

It's like the deaerator thingy (never saw one until matchless put a picture up so I google them) on a sealed system what the hell do you need a deaerator for?

It's all just so they can justify charging £800-900 just for a combi swap.

Who are we talking about?

 

[Millsy 82]

Ah the one we shall not name

 

[king of pipes]

Leave it ! You'll upset him you two

 

[Scott_D]

Don’t vaillant recommend one in the storage combi?