long term water heater costs

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bukzin

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Looking for thoughts on long term natural gas costs for
a multi-family building.

Here is the set-up:
80 year old house converted to a three unit building (college students)
it has four bathrooms and 10 bedrooms
owner pays for hot water (nat. gas)
currently has two 30 old W/H that keep up with the demand
no laundry hook-ups (washer and dryer are on a seperate meter)


The question is, which would have a lower energy expense, long term,
one 60 gallon unit or two 30 gallon units?

Thanks for your thoughts,
Bukzin in California
 
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Kordts

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That's not enough capacity. I would go with a tankless, if possible. That would have the lowest operating costs. If not, a commercial unit with high recovery. My last choice would be two 50 gallon heaters in series.
 

Kordts

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Noritz makes a residential unit that produces 13.2 GPM. Since this is Cali, it might be able to be mounted outside.
 

Jadnashua

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Two in series, plumbed with bypasses, allow you to do maintenance or repairs on one while the other tries to keep up. takes some extra valves, but may be worth it.
 

Cass

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The reason your 2 / 30 gal. gas heaters are working well is that a 30gal. gas heater will recover much faster than a 50. Your heating 40% less water in a 30gal. making the recovery time much faster. You also have 2 burners heating the 60 total gallons instead of 1 heating 50. What you have is working without any complaints, stick with it. If you need to you can have a gas surcharge that gets applied to the rent when the price of gas gos up. Just put it in the lease. To save $$$ you could also install low flow shower heads but I would opt for the gas surcharge on the lease.
 

Geniescience

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they are right. The previous three posts all give good reason NOT to replace the current setup.

When I read your original question, I thought you had to change things. If it works now, don't change anything.

It is true that two small heaters lose more energy when just sitting there holding hot water and waiting for demand, but that standby loss is minimal and negligeable, probably for you as it is for most people in most circumstances. If you were in a cold climate and you were trying to minimize long-term standby losses, you would have every reason to take into consideration this small small constant loss.

The fact that "a single large heater... compared to two small ones... " is not relevant to your situation. You have tenants, not family. Furthermore, you have no reason to throw away a working system.

david
p.s. to lower standby heat losses, seal the heaters airtight somehow, anyhow. Even just by draping a big plastic tarp over them (on top of a spacer), to prevent warm air from flowing up and away. Blocking airflow is a principal means to save heat.
 
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hj

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?

p.s. to lower standby heat losses, seal the heaters airtight somehow, anyhow. Even just by draping a big plastic tarp over them (on top of a spacer), to prevent warm air from flowing up and away. Blocking airflow is a principal means to save heat.

What does that mean? And how would you do it?

Unless the jacket of the heater is warm/hot, there is very little heat escaping from it. The majority of heat loss with a gas heater is up the center flue, and I would not suggest making that "air tight", nor would I recommend making ANY gas heater "air tight" because that creates a perfect scenario for a heater that has to be constantly relit, or exudes carbon monoxide.
 

Geniescience

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i missed that this is nat.gas in the first post.

the big enclosure 'round the top of it is what i do in electric HW heater country. It lowers convection losses.

Any additional layer. Otherwise, warm air is constantly sliding away up to the ceiling, and cooler air comes into contact with it and needs to be heated up, etc.


david
 
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