Multiple demand water heaters

Status
Not open for further replies.
B

bbenigni

Member
Location
Miami, Fl, USA
Im going to start off by saying that i believe the answer is that there is no demand factor that can be applied in this scenario.

I am working on a "Lodging." less than 15 people sleeping facilities in 8 bedrooms, 2 meeting rooms and a laundry room. No cooking facilities, so not a dwelling unit of any kind.

The customer is requesting on demand heating, and wants a 13kW on demand water heater for every 2 bedrooms and 1 for the laundry.

Based on my calculations their service is WAY too small to accommodate 65kW of water heaters. Is there any demand factor that I might be able to apply here?

Everything I have found deals with kitchens (220.56 where it mentions water heaters, but only for kitchens)

I believe I am going to have to recommend storage type heaters.
 
ron said:
Either storage type or service increase is in order.

I think this will happen as folks install multiple electric vehicle chargers in their home also.
Click to expand...

I think what will happen sooner is load shedding devices that will cut out certain loads when others are being used so as to prevent service upgrades and spike uses on the grid.
 
Sierrasparky said:
I think what will happen sooner is load shedding devices that will cut out certain loads when others are being used so as to prevent service upgrades and spike uses on the grid.
Click to expand...

We've had them years here at the house on the water heater and AC. First time the AC was shed, I didnt know about the meter, so I go out troubleshooting it. :lol:
 
Has anyone ever run across the scenario where the customer thinks he knows the code because he found a copy of the NEC?

Unfortunately he believes that his building (he is renovating an 8 unit apartment into a single lodging facility, therefore qualifying as a new construction per the bldg code), will continue to classify as a dwelling unit, and therefore should apply 220.82 to take a 40% demand factor off everything above 10kVA.

When i explained the logic behind it, if you have all 8 showers running at once, which is likely, it defeats the purpose of having demand factors which exist for applications where not all load will be active at once, he was not too thrilled.

I figured i would check with you all to make sure that i wasnt missing something that could be applied in this scenario, but thanks for confirming that i have some semblance of sanity left. Cheers.
 
Open the page for him to the definition of dwelling.... It is not a dwelling once he changes the design but if the code official wants to call it that and give a variance. The likelihood of all boarders using the water heater at one time is small but it could happen. I assume this is a conference area so in the mornings there may be alot of showering....

Again the inspection department may give a variance but I would get it in writing.
 
Several times I have gotten calls from people who have purchased an electric tankless water heater they want me to install (the electrical part, not the water part.). I'll go over to take a look. They will typically be in a middle unit attached condo with a 125 amp panel. The box clearly states it needs 3 x 40 amp 2 pole breakers. They have a hard time understanding that 120 extra amps is not going to fit in their panel nor can I run a bigger service to their unit. I always refer people calling about these to a plumber friend who does gas tankless units. Nobody has a big enough service to support these properly. The bigger the house, the bigger the heater has to be, and the bigger the electrical demands.
 
Last edited:
Coppersmith said:
... I always refer people calling about these to a plumber friend who does gas tankless units.
Click to expand...


If natural gas is available, that will be a lot cheaper too. If they would need to use propane, then costs will be closer, but probably still better than electric storage heater(s). Depends on regional and seasonal energy prices.
 
Coppersmith said:
Several times I have gotten calls from people who have purchased an electric tankless water heater they want me to install (the electrical part, not the water part.). I'll go over to take a look. They will typically be in a middle unit attached condo with a 125 amp panel. The box clearly states it needs 3 x 40 amp 2 pole breakers. They have a hard time understanding that 120 extra amps is not going to fit in their panel nor can I run a bigger service to their unit. I always refer people calling about these to a plumber friend who does gas tankless units. Nobody has a big enough service to support these properly. The bigger the house, the bigger the heater has to be, and the bigger the electrical demands.
Click to expand...

GoldDigger said:
If natural gas is available, that will be a lot cheaper too. If they would need to use propane, then costs will be closer, but probably still better than electric storage heater(s). Depends on regional and seasonal energy prices.
Click to expand...

Gas or propane would be better than electric as I don't know that gas has demand use meters yet. With most electrical utilities going to demand use or tiered rates electricity will be the worst in terms of cost unless you have solar or wind.
 
Status
Not open for further replies.
Top