Hot Water Temperature supply to commercial kitchens

[MedicineEng]

Hi All:

With the current energy prices going through the roof due to the war on Ukraine, there is new found interest among our senior management on energy savings in our property.
Proposals that in the past were hitting deaf ears with the remarks of :"This is not the way to that we do things around here" or " We are a luxury high end 5 star property and this is not our service standard" are now met with: "Why did it take so much time for us to implement this?" and "What other proposals does Engineering have?"

One of the measures that I was considering was to drop the setpoint temperature on our commercial kitchens loop from the usual 65C to around 50~55C, like our other plumbing water loops.
As per my understanding, kitchen hot water loop is kept at higher temperature for cleaning and sterilizing purposes:
1. General cleaning- it helps with degreasing and makes washing more effective
2. Sterilizing- assuring that dishwashers' final rinse is kept around 80C

I was looking if there was any standard or guideline that specifically points out for this 65C setpoint and I couldn't find any. I found some guidelines regarding Legionella control, but we can run lower hot temperatures as we have chlorine dioxide injection on hot and cold water for this purpose.

So basically my reasoning is that is 65C is an old industry standard and doesn't take into consideration development on detergents' chemistry or if the booster heaters at dishwashers are capable to raise the temperature to the required 80C.

If I cover these 2 bases, I believe it would be safe and it wouldn't go against any code or guideline to drop the temperature of the hot water loop by at least 10C.

Any thoughts on this?

Thanks for your help

 

[btrueblood]

Yes, I think it would be reasonable to do what you are suggesting. Would add local temperature gauges at the dishwashers to ensure the rinse cycle reaches 180F/80C. You should talk to the local jurisdiction for food safety/health and make sure there are no local codes that would need to be considered.

 

[dik]

Can you use 'in line' water heaters? I understand they are more energy efficient. Maybe they don't work with commercial applications.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Do you feel any better?

-Dik

 

[EdStainless]

In the US these requirements vary by state.
OSHA dose set limits on sinks that can be used for hand washing, 110F-120F.
Dishwashing requires hotter water, I have seen a range from 140F-160F
Final rinse is usually 180F minimum.
The most common arrangement that I have seen is supplying the kitchen with either 120F or 150F water.
The 150F requires tempering mix valves on the sinks.
And then an inline boost heater for the dishwashing.
Even though these are inline they usually have a small tank (5-10 gal).
I have seen them both electric and gas fired.
They are rated in continuous flow at temp rise of 40F and 70F (usually).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[FACS]

Who are the people that can shut you down or fine you if this temperature is not maintained?
Ask them.

 

[Compositepro]

Hot water boosters are common pieces of restaurant equipment.

https://www.google.com/search?client=firefox-b-1-d&q=commercial+hot+water+booster

 

[TugboatEng]

If your hot water heating is done with gas and your dishwashers are electric, the extra heating required for your dishwashers could exceed any savings elsewhere as electric heat is substantially more expensive. Here in California, the equivalent energy cost for electricity can be as high as 4x the same energy for gas.

 

[itsmoked]

Along with Tug's point I'd add that having one water heater is way less traumatic than multiple ones. The inline ones seem to last a fraction of the time the usual big tank ones do.

I'd stick with the big one.. Put is at whatever temp you need for sterilization requirements then use mixing valves for all the other applications. You can use one for handwashing temps and one for human based pots and pans cleaning temps, etc. Two or three or five mixing valves is way less expensive and way less problematic than multiple water heaters.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[MedicineEng]

Thank you all for your comments.

TugboatEng and itsmoked:

Our dishwashers are fitted with either steam or electrical boosters, depending on the location.
The reasoning for this move is that dishwashers are a fraction of the total hot water use in a commercial kitchen and it might be more energy efficient to run the general hot water loop at lower temperatures even if dishwashers boosters need to work more.

We are now running some tests and see if this move works out...