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Tankless water heater temperture?
- Thread starter SCBO1
- Start date
mark handler
SAWHORSE
Scalding is a serious concern.
Human skin burns quickly at high temperature in about 5 seconds at 60 °C/140 °F, but much slower at 53 °C/127 °F it takes a full minute for a first degree burn. Older people and children often receive the most serious scalds due to disabilities or slow reaction times. In the United States and elsewhere it is common practice to put a tempering valve on the outlet of the water heater.
So No.
Human skin burns quickly at high temperature in about 5 seconds at 60 °C/140 °F, but much slower at 53 °C/127 °F it takes a full minute for a first degree burn. Older people and children often receive the most serious scalds due to disabilities or slow reaction times. In the United States and elsewhere it is common practice to put a tempering valve on the outlet of the water heater.
So No.
Paul Sweet
Sawhorse
This is a good question. 2006 IPC 607.1 allows either hot or tempered water to be supplied for bathing or washing purposes in non-residential occupancies. IPC 416.5 says that tempered water shall be delivered from (?) public hand-washing facilities through an ASSE 1070 water temperature limiting device. I think the intent is to limit water temperature to public lavatories, but the verbiage could be construed as allowing either hot or tempered. I would use the temperature limiting device to be safe.
Restaurant kitchens are usually supplied with 140 degree hot water, and have a booster heater to increase it to 180 for the dishwasher.
Restaurant kitchens are usually supplied with 140 degree hot water, and have a booster heater to increase it to 180 for the dishwasher.
Dr. J
Silver Member
I don't have whatever the IMPC is (504.6 of the IPC is about T&P valve discharge), so I can't help determine if it is not allowed by your code. Perhaps if you quote this section.
If it is similar to the IPC, section 501.6 states "The temperature of water from tankless water heaters shall be a maximum of 140°F (60°C) when intended for domestic uses." Also, 501.2 states "Where a combination potable water heating and space heating system requires water for space heating at temperatures higher than 140°F (60°C), a master thermostatic mixing valve complying with ASSE 1017 shall be provided to limit the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less." There is no similar restriction for tank type water heaters.
So what is "domestic". Not defined in any of the I codes. In some sections, "domestic" means "not commercial" (as in domestic vs commercial cooking appliances, dryers, dish/clothes washers, etc). In others it is the entire potable water system as opposed to the fire water system. The common dictionary definition is closer to the first - personal, home-related, household and family etc. One could make the argument that "domestic purposes" is for dwelling units only. I think in this case it really means water intended for human interaction. In other words, a potable water system in a restaurant could have both domestic and non domestic purposes - hand wash lavs and employee showers are domestic; dishwashers, pre-rinse sprays, 3 compartment sinks, mop basins, etc - not domestic.
Next, is this the public bathroom? If so then the IPC would require a tempering valve at the faucet anyway, so don't worry too much about scalding the customers.
So bottom line for IPC code requirements (not talking good design, just code) - If the water heater is a tank type - no restriction on water temperature regardless of use. If it is a tankless type, then the water supplied to lavs and showers needs to be less than 140 deg, other uses can be over 140. If the water heater is used for building heating, then all potable hot water must be less than 140 deg.
If it is similar to the IPC, section 501.6 states "The temperature of water from tankless water heaters shall be a maximum of 140°F (60°C) when intended for domestic uses." Also, 501.2 states "Where a combination potable water heating and space heating system requires water for space heating at temperatures higher than 140°F (60°C), a master thermostatic mixing valve complying with ASSE 1017 shall be provided to limit the water supplied to the potable hot water distribution system to a temperature of 140°F (60°C) or less." There is no similar restriction for tank type water heaters.
So what is "domestic". Not defined in any of the I codes. In some sections, "domestic" means "not commercial" (as in domestic vs commercial cooking appliances, dryers, dish/clothes washers, etc). In others it is the entire potable water system as opposed to the fire water system. The common dictionary definition is closer to the first - personal, home-related, household and family etc. One could make the argument that "domestic purposes" is for dwelling units only. I think in this case it really means water intended for human interaction. In other words, a potable water system in a restaurant could have both domestic and non domestic purposes - hand wash lavs and employee showers are domestic; dishwashers, pre-rinse sprays, 3 compartment sinks, mop basins, etc - not domestic.
Next, is this the public bathroom? If so then the IPC would require a tempering valve at the faucet anyway, so don't worry too much about scalding the customers.
So bottom line for IPC code requirements (not talking good design, just code) - If the water heater is a tank type - no restriction on water temperature regardless of use. If it is a tankless type, then the water supplied to lavs and showers needs to be less than 140 deg, other uses can be over 140. If the water heater is used for building heating, then all potable hot water must be less than 140 deg.
Maybe. Depends on the dishwasher. Some sanitize with cooler water, some have boosters, and some require a high temp water supply. In large commercial/institutional buildings, we frequently provide both a 140+ system and a 120-ish system. These are usually generated at the higher temperature, then tempered down to the lower temperature via a mixing valve. The wash cycles go faster if the water is supplied at the usage temperature rather than waiting for a booster to heat the sump.
steveray
SAWHORSE
And watch that discharge in to the sanitary can not be greater than 140 I believe? 701.7
Yikes
Gold Member
FYI, our County health department, which has its own requirements for restaurant plan check separate from the plumbing / mechanical codes, often requires the kitchen hot water supply to have its own dedicated heater, separate from other uses. They are concerned that someone will turn down the temperature post-occupancy to avoid scalding in the restrooms (or in other non-kitchen facilities on the same heater).
Mr. Inspector
SAWHORSE
416.5 Tempered water shall be delivered from public hand-washing facilities. Tempered water shall be delivered through an approved water temperature limiting device that conforms to ASSE 1070 or CSA B125.3.
607.1 Where required: residential must have hot water. Nonresidental must have hot water for culinary, cleansing, laundry, or maintenance. Nonresidential must have hot water or tempered water for bathing and washing. Tempered water shall be supplied through a temp. limiting device that conforms to ASSE 1070 and shall limit the tempered water to a max. of 110. This provision shall not supersede the requirement for protective shower valves in accordance with 424.3.
Can't find where this is required.
607.1 Where required: residential must have hot water. Nonresidental must have hot water for culinary, cleansing, laundry, or maintenance. Nonresidential must have hot water or tempered water for bathing and washing. Tempered water shall be supplied through a temp. limiting device that conforms to ASSE 1070 and shall limit the tempered water to a max. of 110. This provision shall not supersede the requirement for protective shower valves in accordance with 424.3.
Can't find where this is required.
mark handler
SAWHORSE
RickRick18071 said:
It is telling you "Where required"
That is the tile of the section.
All residential must have hot water.
Nonresidential must have hot water for culinary, cleansing, laundry, or maintenance.
Nonresidential must have hot water or tempered water for bathing and washing.
skipharper
Registered User
The intent of 416.5 is to protect the public so restaurant bathrooms, as one example, would require 110 degree water. The kitchen is not in this equation. Showers and bathtubs already have scald protection in place. If a water heater, be it tank or tankless complies with ASSE 1070 (LOL) it would be good but the answer is not to adjust the thermostat on such heater.