Domestic hot water not showing in simulation results

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Hello,
I'm a new user to eQuest.
My first project is a small 2 level residential building with just a furnace and domestic hot water.
After setting up the model and running a simulation, the result table shows nothing for the Hot Water line which I think isn't right.
Note the Space Heating line does show numbers (from the NG furnace) that do make sense.
I set up the hot water with the SD Wizard by going in the "residential domestic water heating" page and putting:
Heater Fuel: Natural Gas
Heater Type: Storage
Hot Water Use: 60 Gal/Person/Day
Input Rating: 180 kBtuh
Thermal Efficiency: 80%
Tank Capacity: 75 Gallon
Stand-by Loss: 2%/hr
Supply Water: 135 F
Inlet equals ground temperature
Pumping: 0% recirculation

Clearly, I'm doing something wrong but I don't know what it is. Has anyone come across that problem and would have a suggestion?
Thank you very much,
Pascal

Pascal Poudenx's picture
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Joined: 2013-01-09
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The hot water use looks like it may be the issue. A 3 bedroom house (#
beds + 1 = 4 occupants ) will be using 240 gallons per day with the rate
you have.

I would look at some of the defaults RESNET Standard or Building America
has for DHW consumption. I think 45-50 gallons per day for a family of
4 is more realistic.

http://www1.eere.energy.gov/buildings/residential/ba_analysis_spreadshee
ts.html#schedule

I think chapter 3 deals with the rated home.

http://www.resnet.us/standards/RESNET_Mortgage_Industry_National_HERS_St
andards.pdf

Byron D. Burns

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I don't see anything presented that should prevent the hot water consumptions being modeled, though. Everything I can think of to check would be in detailed mode, but one thing that sticks out to me is that you are using the SD wizards, which I haven't much experience with. There may be some causality here.

If you are trying to stick with the wizards (avoid detailed edits) for now, I would suggest trying "stepping up" to the DD wizards - I have never had issues with hot water systems not operating coming out of the DD wizards, and that may solve the issue outright.

If you are in detailed edits, I would start by confirming the inputs you've listed are showing up under the water tab, then I'd also check the hot water usage schedule to ensure it is assigned and isn't itself somehow zeroed out.

Also since you mentioned this is your first project, I'll put forward that I'm a big proponent of learning the ropes with the DD wizards. For most projects, that's where you will want to start anyway due to the added flexibility and timesaving inputs prior to detailed mode, so it makes sense to get familiar sooner than later.

Best of luck!

[cid:489575314 at 22072009-0ABB]

NICK CATON, P.E.

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Joined: 2011-09-30
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