Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

My 15 year old 50 gallon gas water heater needs to be replaced (just
small leak... so far).

Most all the new ones are 40k BTU. My old one was 55k BTU's.

So are the new ones just more efficient and need less gas... or do the
new ones have a lower recovery rate? (can not find stats on old
unit... new units have a recovery rate of aprox 40 gph.

The EF (Energy Factor) on my old unit says .55. The new ones are in
the .58 to .62 range. But can that make up for a 15k BTU difference?

Maybe my old unit was a special "high recovery" model. These are
still around... not to common however.

Thx
Dave-in-Denver

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Dave in Denver wrote:

So are the new ones just more efficient and need less gas... or do the
new ones have a lower recovery rate? (can not find stats on old
unit... new units have a recovery rate of aprox 40 gph.


Recovery rate and energy efficiency are really unrelated.

The EF (Energy Factor) on my old unit says .55. The new ones are in
the .58 to .62 range. But can that make up for a 15k BTU difference?


The EF is really the insulation and the damper in the flue for the non-power
vented units.

Maybe my old unit was a special "high recovery" model. These are
still around... not to common however.

Means it has a larger burner which is why the btu rating is higher.

--
"Tell me what I should do, Annie."
"Stay. Here. Forever." - Life On Mars

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 5, 9:32 pm, Rick Blaine wrote:


Thanks Rick,
Sorry I am being thick here.. are you saying if I get a new one with
just 40k BTU that is will perform like my old 55k BTU?

Thx
Dave-in-Denver

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 5, 11:52?pm, Dave in Denver wrote:
On Jul 5, 9:32 pm, Rick Blaine wrote:

Thanks Rick,
Sorry I am being thick here.. are you saying if I get a new one with
just 40k BTU that is will perform like my old 55k BTU?

Thx
Dave-in-Denver

absolutely not! the 55K BTU models are still avilable home depot
locally sells them.

a 40K BTU will have a much less recovery.

the higher efficenys of today are mostly from the better foam
insulation.

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Rick Blaine wrote:

Dave in Denver wrote:

So are the new ones just more efficient and need less gas... or do the
new ones have a lower recovery rate? (can not find stats on old
unit... new units have a recovery rate of aprox 40 gph.

Recovery rate and energy efficiency are really unrelated.

Other things being equal, eg wall insulation and heat exchange surface,
a gas water heater with a lower recovery rate, ie a lower heat transfer
rate should be more efficient. Changing to a smaller gas orifice would
likely increase efficiency.

Nick

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Dave in Denver wrote:
On Jul 5, 9:32 pm, Rick Blaine wrote:


Thanks Rick,
Sorry I am being thick here.. are you saying if I get a new one with
just 40k BTU that is will perform like my old 55k BTU?

Thx
Dave-in-Denver

No. It will perform different. First it will take longer to recover.
Of course if you don't need that fast recovery (do you ever run out of hot
water?) then that would be a non-issue. It would be hard to say if you have
not tried both. However if you now have a smaller family, like one or more
kids away at college or now on their own, you likely don't need as high a
recovery as before.

It is also possible that the lower recovery may be very slightly more
energy efficient, but that would be hard to say.

--
Joseph Meehan

Dia 's Muire duit

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Dave in Denver wrote:

Sorry I am being thick here.. are you saying if I get a new one with
just 40k BTU that is will perform like my old 55k BTU?

No, what I mean is that a 40K burner will take longer to recover than a 55K
burner, but that everything else being equal (ie same EF), they will use the
same amount of energy.

--
"Tell me what I should do, Annie."
"Stay. Here. Forever." - Life On Mars

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 6, 9:06?am, Rick Blaine wrote:
Dave in Denver wrote:

Sorry I am being thick here.. are you saying if I get a new one with
just 40k BTU that is will perform like my old 55k BTU?

No, what I mean is that a 40K burner will take longer to recover than a 55K
burner, but that everything else being equal (ie same EF), they will use the
same amount of energy.

--
"Tell me what I should do, Annie."
"Stay. Here. Forever." - Life On Mars

the lower recovery burner 40K or even 34K BTU aree all about producing
a cheaper tank.

More expensive high BTU tanks like my PRO model have a higher purchase
price, but tend to have better materials, like brass drain valves,

your bewtter off with a higher BTU tank

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Thanks Gents!!!
This just the info/advice I needed.

I want the same recovery rate that I have now so I will get what are
now call "high recovery" models. And will also like the fact that
these HR units are likely to have better parts.

Thx!

Dave-in-Denver

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 6, 11:38?am, Dave in Denver wrote:
Thanks Gents!!!
This just the info/advice I needed.

I want the same recovery rate that I have now so I will get what are
now call "high recovery" models. And will also like the fact that
these HR units are likely to have better parts.

Thx!

Dave-in-Denver

if your still hot water challenged consider a 75 gallon tank, with 75K
BTU, just make certain it will physically fit.

Frankly I dont know why anyone buys a small and low BTU tank.

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

" wrote:

Frankly I dont know why anyone buys a small and low BTU tank.

For size, you have to balance your hot water requirements against energy
efficiency. Sure, a larger tank is great for those times when you need a lot of
hot water all at once, but you are going to be paying for that both in the
initial cost as well as the increased heat loss from the larger tank.

For BTUs, I agree a larger burner is better. The problem is that they don't sell
water heaters by component and going with a larger unit gets you into the cost
issues listed above.

--
"Tell me what I should do, Annie."
"Stay. Here. Forever." - Life On Mars

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Rick Blaine wrote:

For BTUs, I agree a larger burner is better...

No. Heat exchangers with smaller burners and lower heat transfer rates
are more efficient.

Nick

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 6, 3:09?pm, wrote:
Rick Blaine wrote:

For BTUs, I agree a larger burner is better...

No. Heat exchangers with smaller burners and lower heat transfer rates
are more efficient.

Nick

well a couple years ago I checked efficeny on a LOT of tanks, they
were all within a few points of one another.

more BTUs definetely makjes for faster recovery

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

On Jul 6, 4:25?pm, wrote:
wrote:
more BTUs definetely makjes for faster recovery

It also makjes for less energy efficiency.

Nick

check specs, theres very little difference

besides in winter heat lost goes to help keep building warm

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Gents,
I called tech support (at Bradford White) to understand the BTU vs.
efficiency thing.

Short version (all my brain could hold on to) is the efficiency
numbers all take into account the BTU energy what ever that volume
happens to be... so it is an apples-to-apples comparison to look just
at the Recovery Efficiency (ie 79%) or the Energy Factor (ie .58) from
one unit to the next (of course assuming each has the same gallon
capacity).

HOWEVER... if one unit has 2" of insulation and the next unit has
just 1" of insulation, and they both have the same efficiency
ratings... well the 2" unit is being helped because of its R-factor so
then the 1" unit would have better "blowtorch only" numbers.

Dave-in-Denver

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

So are the new ones just more efficient and need less gas... or do the
new ones have a lower recovery rate? (can not find stats on old
unit... new units have a recovery rate of aprox 40 gph.


What I learned (hopefully correctly)...
- BTU's do make a big difference in recovery performance.
- Efficiency numbers all take into account BTU's so it is OK to make
comparison of those numbers (same gallon size however).

What I did...
I picked out a High Recovery water heater that also has extra
insulation and a Mag rod (not alum.).
- Has 65kBTU rather than the standard 40kBTU.
- Energy Factor, Est annual cost, first hour rating, gallon
recovery.... all are higher/better than the standard water heater of
same size and Mfg/model family.

Bradford White, State, AOSmith each had comparable units as expected.
(OK maybe Bradford White had a slight advantage but only a lab rat
with a PhD could tell the difference in the real world.)

I picked a Bradford White product for two small reasons.
1) my plumber likes and can get a better deal on B/W because of repeat
business at his supplier.
2) The Bradford White has a Magnesium anode rod where the others had
Aluminum... and posts I saw said the Mag rods were better.

Thanks everyone for your help!
Dave-in-Denver

Water Heater - More Efficient? 40k BTU vs. 55k BTU
 

Dave in Denver wrote:

I picked out a High Recovery water heater that also has extra
insulation and a Mag rod (not alum.).
- Has 65kBTU rather than the standard 40kBTU.

It might be more efficient with the smaller burner.

Nick