MIXING VALVE on water heaters ( residential)

[hvactech83]

okay so lately i see all new home builder installing  mixing valves on the  tank water heaters . i heard ( from a person who works for builder that its code that new home builder must include it )  now i also have has afew service call from some customers that ther having issue with  ther mixing valve  to fail and not deliver proper water temp  and so i replace them . now my question is ... is it code and is it a must to have it installed ?  does it  have to be ther ? can we just cancel it if we want to ? i don't see nothing in our code book talks about it ? also  mixing valves  what th point really , just to mix cold water for domestic so u don't get burned ? that's it?

[Hgye]

It is code in Ontario if you are using a tank as per OBC.  They are not required for tankless.  Electric tanks must be kept at 140F minimum, but the maximum temp from most of your faucets is 120F.  Kitchen and laundry excluded.  Hence the mixing valve.

[Admin]

See OBC Article 4.6.5,

7.6.5. Water Temperature Control

7.6.5.1. Maximum Temperature of Hot Water
(1) Except as provided in Sentences (2) and 7.6.5.3.(1), the maximum temperature of hot water supplied by fittings to fixtures in a residential occupancy shall not exceed 49°C.
(2) Sentence (1) does not apply to hot water supplied to installed dishwashers or clothes washers.

7.6.5.2. Showers
(1) Except as provided for in Sentences (2) and (3), all valves supplying fixed location shower heads, shall be individually pressure-balanced or thermostatic-mixing valves, conforming to ASME A112.18.1 / CAN/ CSA-B125.1, "Plumbing Supply Fittings".
(2) An individually pressure-balanced or thermostatic-mixing valve shall not be required for showers if a single temperature water supply for such showers is controlled by a master thermostatic-mixing valve conforming to CAN/ CSA-B125.3, "Plumbing Fittings".
(3) Deck-mounted, hand-held, flexible-hose spray attachments are exempt from the thermal shock requirements of Sentence (1).
(4) Pressure-balanced or thermostatic-mixing valves shall be,
(a) designed so that the outlet temperature does not exceed 49°C, or
(b) equipped with high-limit stops which shall be adjusted to a maximum hot water setting of 49°C.

If a tankless is also being used for space heating you will need to install a mixing valve on the domestic hot water side of the system, as the temperature is usually set to 140F.

I have also heard it's best to increase the water temperature on tank type water heaters to ensure there is no bacteria in the water.  The mixing valve is used to lower the hot water to a safe 120F.

[hvactech83]

Thank you guys for the info .
I don't get it thou   water heater have got temperature setting on its gas controls  , why can't we rely on it ?

[bster352]

the control on a water heater is not totally accurate and can get changed quite easily. A water temperature of 120°F does not kill the Legionella bacteria; a minimum temperature of 140°F is required at which Legionellae dies in 32 minutes. Hence it is recommended that the water heater be set at a temperature of 140°F. The Legionella disinfection range is 158 – 176 °F.

Thank you guys for the info .
I don't get it thou   water heater have got temperature setting on its gas controls  , why can't we rely on it ?

[hvactech83]

i see .. i didnt know that . thank you .

[Porcupinepuffer]

If we're doing a re/re on an existing tank that never had one because this wasn't required at the time, are we ok? Or are we supposed to be installing a mixing valve and upping the tank temperature when replacing a tank?

[Admin]

Yes, when you replace a tank type water heater you must satisfy OBC Article 7.6.5.1.

Download the Redmond Williams document - Here

Tankless water heaters do not require a mixing valve, as long as the controller cannot be adjust higher than 120F.

The OBC was amended by O. Reg. 23/04 to require the maximum temperature of hot water supplied by fittings to fixtures in residential occupancies not to exceed 49C. This requirement is found in Article 7.6.5.1, which states:
(1) Except as provided in Sentences (2) and 7.6.5.3.(1), the maximum temperature of hot water supplied by fittings to fixtures in a residential occupancy shall not exceed 49C.
(2) Sentence (1) does not apply to hot water supplied to installed dishwashers or clothes washers.

Where a hot water tank is replaced in an existing residential building, this code amendment requires upgrading of the water distribution system to limit hot water temperature to not more than 49C at specified plumbing fittings. A common method of complying with this requirement has been the installation of a master mixing valve immediately downstream of the hot water tank. We are aware of the installation and temperature control difficulties that may arise during the replacement of certain hot water tank configurations and, therefore, acknowledge that the master mixing valve solution may not be the most appropriate compliance solution in every situation.  Sentence 7.6.5.1.(1) is a performance requirement that does not preclude the use of other means of compliance. Other options for compliance may include:

Point of use mixing valves:
The OBC was amended in 1993 to require pressure balanced or thermostatic mixing in showers and combined shower/bathtubs. One may wish to consider installing point of use thermostatic mixing valves on the remaining fixtures that require temperature control. Point of use mixing valves are particularly suited in situations where there is substantial heat loss in the hot water distribution piping between the hot water storage tank and the fixture.

TAFR valves:
Temperature actuated flow reduction (TAFR) valves may be installed by the homeowner and are intended for use on individual fittings. These valves will automatically reduce
water flow when the outlet temperature exceeds 49C. TAFR valves are particularly suited for some retrofit installations. Tankless water heater with max +/-10C temperature control:
The advantages of an instantaneous water heater include:
- Maintain accurate water temperature continuously
- Eliminate the need for mixing valves
- Provide hot water on demand
- Potentially save energy by avoiding hot water storage

Please call me at your convenience if you have any questions.

Sincerely,
Alek Antoniuk
Co-ordinator, Code Development
Building & Development Branch
777 Bay Street, 2nd. Floor
Toronto, Ontario M5G 2E5
tel. 416 585-6456
cell. 416 725-4889
fax. 416-585-7531
e-mail alek.antoniuk@mah.gov.on.ca

[Porcupinepuffer]

Look at me reviving an old thread!

I got some follow up questions about this as I still see many companies just installing re/re tanks in the old school method with zero use of a mixing valve; Or yanking out existing mixing valves like they never even existed. I've even seen several customers want them yanked out from issues.

So is there any documents showing we actually need to have the tank set to a higher than 120 degree temperature for killing off this bacteria?

I understand the reasoning about the bacteria, but it is written somewhere that this is a reason for the mixing valve? Or is it just because the theory is that this mixing valve is a safer way of keeping people from somehow getting scalded?

Are you other tank installers re adapting with existing mixing valves or installing new ones?

[walker]

I was told this by a College of Trades Enforcement Officer regarding mixing valves:

"I have been asked to contact you with regards to your questions about the installation of a Mixing Valve
being performed by a TSSA Gas Certificate holder.

Your question falls under two Acts. The Ontario College of Trades and Apprenticeship Act, 2009 and the
Technical Standards and Safety Act, 2000.

I understand Malavika from the College's Compliance and Enforcement Division has already provided the
Plumbers Scope of Practice that highlights the tasks found within the scope, that speaks to the installation
of a mixing valve and the requirement for a licensed plumber to do this work by law.

Regarding the TSSA Act and the ability for a Gas Certificate holder to install gas fired appliances. Attached to this email
is a word doc with text taken from the TSSA Act that shows the Scope of a G1, G2 and G3 certificate holder. You will notice
that I've highlighted the most important part to consider when discussing the installation of a mixing valve.
The mixing valve is not essential to the operation of the hot water tank. The hot water tank will operate with or without
the mixing valve being installed.
I hope this helps to clarify the requirements under both Acts with regards to the installation of a mixing valve during the
installation of a new hot water tank.

In order to install a mixing valve. The Gas Fitter would have to be a member of the College as a Plumber
with an apprentice class membership or a journeyperson class membership."

There position on mixing valves is that a gas fitter may not under circumstance touch a mixing valve.

[Admin]

I know there are big rental companies in Ottawa that are making their gas fitters install mixing valves, I guess illegally.  I suppose all the gas fitter should do is provide the client with a letter stating the building code requires a mixing valve and that they need to hire a licensed plumber to install it.

[walker]

Yes I've since started refusing to do them. We were being told that we are allowed too install/replace them. So I asked the TSSA and OCOT myself what was allowed.

[Porcupinepuffer]

I never thought to look further into it being out of our scope when it's often installed so close to the tank. Anyways, that's awesome. I can sleep better now.

[Admin]

Has the TSSA replied yet?  The OCOT obviously wants to interpret things a certain way, but you could argue the mixing valve is essential.

Ontario Regulation 215/01 says,

G.2 certificate
   21.  (1)  A person who is the holder of a G.2 certificate may install, inspect, alter, purge, activate, repair, service or remove a natural gas or propane appliance that has an input of 400,000 Btuh or less and the equipment and accessories essential to its operation.  O. Reg. 215/01, s. 21 (1).

The definition of essential is,

absolutely necessary; extremely important.

If the Building Code requires a mixing when a water heater is replaced, would that not mean it is essential?  It's only inconveniencing home owners with more costs not allowing the gas fitter to do this.

What if we said, The vent is not essential to the operation of the hot water tank. The hot water tank will operate with or without the vent being installed. 

The mixing valve just like the vent needs to be installed for safety.  The gas fitter should be allowed to do this.

[walker]

TSSA said to ask the OCOT lol.

[tenletters]

Has the TSSA replied yet?  The OCOT obviously wants to interpret things a certain way, but you could argue the mixing valve is essential.

Ontario Regulation 215/01 says,

G.2 certificate
   21.  (1)  A person who is the holder of a G.2 certificate may install, inspect, alter, purge, activate, repair, service or remove a natural gas or propane appliance that has an input of 400,000 Btuh or less and the equipment and accessories essential to its operation.  O. Reg. 215/01, s. 21 (1).

The definition of essential is,

absolutely necessary; extremely important.

If the Building Code requires a mixing when a water heater is replaced, would that not mean it is essential?  It's only inconveniencing home owners with more costs not allowing the gas fitter to do this.

What if we said, The vent is not essential to the operation of the hot water tank. The hot water tank will operate with or without the vent being installed. 

The mixing valve just like the vent needs to be installed for safety.  The gas fitter should be allowed to do this.

It's really not essential. It's required for building code, but a plumber is required to do them.

The water heater will function just fine without it, so being essential is arguable.

TSSA will not give an answer and OCT will say you have to be a plumber. I've gone through this.