# Commercial dishwasher question



## The Dane (Feb 19, 2015)

The local volunteer fire department that I used to be a member of and now support by helping out when I can. Have asked me to install a used commercial dishwasher in their non commercial kitchen. I got a Hassel on my hands but I'm determined to get it done for them.

First off we are in MN so its UPC code. They want to take out cabinets and current kitchen sink and convert it to a commercial dishwasher. 

The dishwasher has an electric heat booster. It has a 2" drain 6" above the floor that was previously hooked up to pvc pipe from what I'm told. It had a 3/4" copper water supply line before. 

It has the pressure reducer and all still ready to go and just needs to be hooked up with new water and drain. 

It will be used 2 times a month when they feed their 20 some people dinner at their meetings and not much more. 

My 2 main questions are these. 

1: With minimal use like that and there being a pressure reducer would it be possible to use the existing 1/2" water line despite the original one being 3/4" or would that not function? 

2: Can I open the wall by the existing drain, eliminate the original drain arm and install a tee close to the floor and connect the dishwasher drain directly to that tee?

It is a Hobart model AM14 or AM14C

Oh yeah and they sprung this on me and would like to see if they can get an answer tonight to whether this will work or not so they can demo the old kitchen counter tomorrow. 

Here are all the pictures the guys took of the original installation what I took of the things they had now disconnected and sitting in a trailer.


























































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## The Dane (Feb 19, 2015)

Also the existing drains should be cast iron underground and eigter galvanized or copper in the wall.

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## MACPLUMB777 (Jun 18, 2008)

The Dane said:


> The local volunteer fire department that I used to be a member of and now support by helping out when I can. Have asked me to install a used commercial dishwasher in their non commercial kitchen. I got a Hassel on my hands but I'm determined to get it done for them.
> 
> First off we are in MN so its UPC code. They want to take out cabinets and current kitchen sink and convert it to a commercial dishwasher.
> 
> ...


First the drain is required to connected to a Indirect Drain IE; a floor sink, your ideal has no p-trap,
Second that dishwasher required a 3/4" supply, remember this is"NOT" your family dishwasher, It depends on Volume 
of water to support Its function,
Third it may require RPZ backflow to protect the potable water supply,


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## The Dane (Feb 19, 2015)

MACPLUMB777 said:


> First the drain is required to connected to a Indirect Drain IE; a floor sink, your ideal has no p-trap,
> Second that dishwasher required a 3/4" supply, remember this is"NOT" your family dishwasher, It depends on Volume
> of water to support Its function,
> Third it may require RPZ backflow to protect the potable water supply,


From what little I can gather in the code book it requires a backflow prevention device one is already installed in the piping. The drain should be a floor sink yes. At first I thought I could maybe put a 2" ptrap right on the floor and a 3"X2" coupling on top as a bowl and have enough room to make the dran go in to it indirectly but thinking more about it that would. So in the end I'll probably have to bust up a little concrete and put a floorsink in there.

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## Tango (Jan 13, 2018)

In our code it is illegal to install used fixtures. Plus you install that and you may have to guarantee it for a minimum 3 months. Or if you fix it now you own it. Gotta provide a detailed estimate before you repair it otherwise they win in court.


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## The Dane (Feb 19, 2015)

Tango said:


> In our code it is illegal to install used fixtures. Plus you install that and you may have to guarantee it for a minimum 3 months. Or if you fix it now you own it. Gotta provide a detailed estimate before you repair it otherwise they win in court.


We are fully legally allowed to install what ever we want to as long as it is an approved appliance.

I dont have to worry about it as I am donating my time as a community service and I made them fully aware that there is no such thing as a guarantee that a used product will work fine for a day or a decade.

Its basically the same as an a houseowner being allowed to do his own plumbing. I am considered a part of their group so its not on me personally.

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## The Dane (Feb 19, 2015)

MACPLUMB777 said:


> Second that dishwasher required a 3/4" supply, remember this is"NOT" your family dishwasher, It depends on Volume
> of water to support Its function,
> Third it may require RPZ backflow to protect the potable water supply,


I was thinking since the building pressure is around 50psi and there is a 25psi pressure reducer on the dishwasher line. The amount of volume that 1/2" line can produce a minute would be enough to to supply the dishwasher. I think the dishwasher is only supplied with a 3/4" in case you have 20-25psi avaliable without the reducer and therefore would need that bigger size. 

So in this way the dishwasher is still fed by the pressure and size it needs and the pressure reducing valve simply serves as a type of bridge that converts higher pressure smaller pipe to lower pressure bigger pipe.

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## skoronesa (Oct 27, 2015)

The Dane said:


> I was thinking since the building pressure is around 50psi and there is a 25psi pressure reducer on the dishwasher line. The amount of volume that 1/2" line can produce a minute would be enough to to supply the dishwasher. ...............


I was thinking the same thing but didn't say it because I think the biggest factor is the length of the run and the fittings.

How long is the 1/2" run and more importantly how many 90's? 90's add up to a lot of resistance.


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## The Dane (Feb 19, 2015)

skoronesa said:


> I was thinking the same thing but didn't say it because I think the biggest factor is the length of the run and the fittings.
> 
> How long is the 1/2" run and more importantly how many 90's? 90's add up to a lot of resistance.


15'-20' 2-4 90° everything water is oversized in the building so it will never loose pressure because of too many things getting used.

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## RichardBull (Jan 7, 2021)

Waste of time. Install two nice Bosch dishwashers one on each side of the K-sink and forget about it.


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## Toli (Nov 7, 2015)

I don't think a 2" drain will handle the discharge fast enough. You probably already know this, but it's probably a high temp machine, so plastic pipe won't work on the drain.

Also, what's their water heater situation? The booster heater only raises the incoming temp a fixed amount so the hot water supply needs to be sized accordingly.


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## The Dane (Feb 19, 2015)

Toli said:


> I don't think a 2" drain will handle the discharge fast enough. You probably already know this, but it's probably a high temp machine, so plastic pipe won't work on the drain.
> 
> Also, what's their water heater situation? The booster heater only raises the incoming temp a fixed amount so the hot water supply needs to be sized accordingly.


2" discharge is what the dishwasher has and was piped to before. I'm going to add a floorsink and take it that it can't be a pvc sink so ill probably run cast the couple feet over to it from the original underground cast drain. WH is a standard residential 50 gal electric and I think its already set a but on the high side.

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## The Dane (Feb 19, 2015)

RichardBull said:


> Waste of time. Install two nice Bosch dishwashers one on each side of the K-sink and forget about it.


They already have a domestic DW but they never use it because someone would have to come back later to empty it.

I would have tried to talk them out of it but they already bought it so now I'm stuck with helping with this mess.

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## Toli (Nov 7, 2015)

The Dane said:


> 2" discharge is what the dishwasher has and was piped to before. I'm going to add a floorsink and take it that it can't be a pvc sink so ill probably run cast the couple feet over to it from the original underground cast drain. WH is a standard residential 50 gal electric and I think its already set a but on the high side.
> 
> Sent from my SM-G970U using Tapatalk


Might be ok with that heater if they are only doing a few racks when they use it. I think that machine will do roughly a rack/minute. I'm guessing here, but if it requires 2 gallon/cycle that's 2 gal/minute which means that dish machine will be out of hot water in 17ish minutes. Maybe that's ok? the 2 gal/cycle sticks in my head for some reason which I don't remember. If it uses less that that the heater will stretch farther.

Another thing to check on- building codes may require a hood over a high temp dish machine.


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## The Dane (Feb 19, 2015)

Toli said:


> Might be ok with that heater if they are only doing a few racks when they use it. I think that machine will do roughly a rack/minute. I'm guessing here, but if it requires 2 gallon/cycle that's 2 gal/minute which means that dish machine will be out of hot water in 17ish minutes. Maybe that's ok? the 2 gal/cycle sticks in my head for some reason which I don't remember. If it uses less that that the heater will stretch farther.
> 
> Another thing to check on- building codes may require a hood over a high temp dish machine.


Yes its only a couple racks at a time they would do and not any other hot water usage at the same time. I think it said 1.5 gallon per wash but im not sure. Is said you could up the wash cycle to 90 seconds if needed.. It did have a hood where it was installed before but I do not believe it is required by code besides there is a big difference between a couple cycles and 20 in a row at an actual restaurant. So I told them to keep it just in case but it should not be needed.

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## SchmitzPlumbing (May 5, 2014)

i agree with an open site drain. also agree with an exhaust hood. next thing is making sure you have soft water or it will lime up really fast. do you have the right power for the booster? i just did a big dishwasher last month. $60 grand just for the unit. mine had a built in ac unit on it so we got rid of the exhaust hood.


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## The Dane (Feb 19, 2015)

SchmitzPlumbing said:


> i agree with an open site drain. also agree with an exhaust hood. next thing is making sure you have soft water or it will lime up really fast. do you have the right power for the booster? i just did a big dishwasher last month. $60 grand just for the unit. mine had a built in ac unit on it so we got rid of the exhaust hood.


There is an electrician in the fire department and he is running new power to it. Water is through the town and its good quality so no need to worry there. It will be a new floor sink for drain and I'll supply it with the 1/2" line as I believe it will work fine. Should it actually require a 3/4" line then I'll just change it but I'm donating my time on this so I'm not going through all the extra trouble to run a new 3/4" line over when there is a 1/2" right there and I belive it will handle it. I don't believe there is a hood required by code so because of the low usage it will see I am fine with not putting the hood in at first and if we feel like it might be best then we will put it in later.

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## sparky (Jan 8, 2014)

The Dane said:


> The local volunteer fire department that I used to be a member of and now support by helping out when I can. Have asked me to install a used commercial dishwasher in their non commercial kitchen. I got a Hassel on my hands but I'm determined to get it done for them.
> 
> First off we are in MN so its UPC code. They want to take out cabinets and current kitchen sink and convert it to a commercial dishwasher.
> 
> ...


1/2" will serve it ok if 3/4 is not available,just go from 1/2" to 3/4" as quick as possible,in other words at the wall put a 3/4"x1/2" reducer then a 3/4" ball valve to the washer,it's better than nothing and it will work,check your codes and health dept as to drain hookup


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## sparky (Jan 8, 2014)

The Dane said:


> I was thinking since the building pressure is around 50psi and there is a 25psi pressure reducer on the dishwasher line. The amount of volume that 1/2" line can produce a minute would be enough to to supply the dishwasher. I think the dishwasher is only supplied with a 3/4" in case you have 20-25psi avaliable without the reducer and therefore would need that bigger size.
> 
> So in this way the dishwasher is still fed by the pressure and size it needs and the pressure reducing valve simply serves as a type of bridge that converts higher pressure smaller pipe to lower pressure bigger pipe.
> 
> Sent from my SM-G970U using Tapatalk


Correct


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## skoronesa (Oct 27, 2015)

sparky said:


> 1/2" will serve it ok if 3/4 is not available,just go from 1/2" to 3/4" as quick as possible,in other words at the wall put a 3/4"x1/2" reducer then a 3/4" ball valve to the washer,it's better than nothing and it will work,check your codes and health dept as to drain hookup


I agree, upsize to 3/4" before the prv.


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