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Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 6:54 pm
by oliver power
Wife is having a walk-in tubb installed. Walk in tub company says our 14 year old 40 gallon electric hot water tank won't cut it. Need 65 - 70 gallons minimum. So, is it time to install my in-direct hot water tank, and heat with boiler? Or install an 80 gallon electric hot water tank. If heating with boiler, I'd have to run year round. That means I'd have to build an insulated room around the boiler, so that it doesn't compete with central air. Or, at least insulate the primary loop. Thought it would be nice to hear opinions from fellow members before deciding. Thanks, Oliver

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 7:15 pm
by Carbon12
If she wants to use the tub during the heating season, I think you'll be glad you went with electric :D
Especially when it's below zero outside and the KA2 is working hard. You could always plumb the coal boiler to the hot water heater with some creative plumbing.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 7:23 pm
by Rob R.
Any idea what the fill rate will be for the tub? Do you care how long it will take to reheat the tank?

An 80 gallon indirect is serious business, I have one and I can't imagine a KAA-2 running it very well.

80 gallon electric with a recirc loop through the tankless coil would be cost effective and also summer friendly.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 7:37 pm
by tsb
Your profile doesn't give your age, but if it's just you and your wife, I would
get a hot water heater powered by what ever is cheapest. Electric or propane.
I used to have two 40 gallon tanks in series but one of them pooped out so now
I only have one. I loop the tank with the DHW coil in the Binford using a potable
pump with a thermostat set to 120 and the propane tank thermostat set at 100.
With only my wife and I in the house, I have plenty of hot water and the recovery is
very quick. I don't think the gas burner came on all winter. I really idle the Binford
during the summer and the recovery is not as fast, but I don't use that much hot water either.
Hope this helps.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 9:29 pm
by oliver power
Carbon12 wrote:If she wants to use the tub during the heating season, I think you'll be glad you went with electric :D
Especially when it's below zero outside and the KA2 is working hard. You could always plumb the coal boiler to the hot water heater with some creative plumbing.
Yes, Kaa-2 was at it's limit last winter, with -8*, and wind howling. Should I have needed to, I have one last trick up my sleeve. That would be to insulate the piping, as to loose minimum heat to the basement. I agree that an electric hot water heater would allow the little Kaa-2 to concentrate on heating rooms. I know I should probably favor electric for that reason alone. Thanks for your opinion. Oliver

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 9:51 pm
by blrman07
Don't abandon the Ka2 in favor of electric. Make sure you do the plumbing so you can switch between the two or put them in series. That way they can assist each other, or just use the electric, or just the boiler, or both together.

Redundancy is your friend.

Rev. Larry
New Beginning Church
Ashland Pa.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 9:52 pm
by windyhill4.2
My $.00000001 opinion... I would add an 80 gallon tank to increase the boiler reservoir,super insulate the tank, run a small circulator 24/7 to keep the water all the same temp,this would help even out the high & low demand periods. Your Kaa-2 doesn't run the burner flat out 24/7 without catching up at times , does it ?? You could hook to an electric water heater using a water to water exchanger,electric elements would only come on when the heat demand is too great for the boiler to keep after.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 9:56 pm
by oliver power
Rob R. wrote:Any idea what the fill rate will be for the tub? Do you care how long it will take to reheat the tank?

An 80 gallon indirect is serious business, I have one and I can't imagine a KAA-2 running it very well.

80 gallon electric with a recirc loop through the tankless coil would be cost effective and also summer friendly.
Hi Rob, Not sure of tub fill rate. Once tub is filled with water, tub has a heater that senses, and maintains the temperature of the water. Yes, I agree, no way would the little Kaa-2 handle an 80 gallon indirect. If I were to go indirect, my thoughts were to help out the 40 gallon electric hot water heater. And should the 40 gallon electric go bad, it would be a lot less money to replace it, than it would be to replace an 80 gallon electric hot water heater. I'm not concerned about recovery time. I do agree that an electric water heater would be summer friendly. I'd be able to shut down the boiler during summer months. So far, it looks like the electric hot water tank is winning this debate. Thanks for your opinion, Oliver

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 10:16 pm
by oliver power
windyhill4.2 wrote:My $.00000001 opinion... I would add an 80 gallon tank to increase the boiler reservoir,super insulate the tank, run a small circulator 24/7 to keep the water all the same temp,this would help even out the high & low demand periods. Your Kaa-2 doesn't run the burner flat out 24/7 without catching up at times , does it ?? You could hook to an electric water heater using a water to water exchanger,electric elements would only come on when the heat demand is too great for the boiler to keep after.
Yes, during the bitter cold days, The Kaa-2 ran flat out, around the clock, yet maintaining the thermostat set points. One night it was -8*, with wind howling. Boiler temp dropped below my design temp of 180*, yet still maintained thermostat temp. So, I know it was at the tipping point. But that was only during the coldest days of winter. Could tell the wife she's not to use the tub those days. Yea Right! Yes, adding capacity to the Kaa-2 would help. 10 gallons would make a big difference.

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 10:19 pm
by Lightning
Why not have a thermo syphon temper tank with the coal boiler water coil to preheat water in series with an electric hot water tank? Best of both worlds and with minimum demand on the coal boiler...

Edit. - and you would have the option to not use the coal boiler in the summer this way...

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 10:34 pm
by oliver power
blrman07 wrote:Don't abandon the Ka2 in favor of electric. Make sure you do the plumbing so you can switch between the two or put them in series. That way they can assist each other, or just use the electric, or just the boiler, or both together.

Redundancy is your friend.

Rev. Larry
New Beginning Church
Ashland Pa.
Yes Larry, if I went with a smaller indirect, it would be plumbed in series in order to help out the 40 gallon electric hot water heater. Summer months I would still have to run the boiler, ONLY for the tub. I'd like to put in the 80 gallon electric water heater, and the indirect. That would be the best of both worlds. However, this tub is costing a lot of money. And I have other business priorities I'm working on. I do Thank You for your input, Oliver

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 10:48 pm
by whistlenut
Another thought is that an 80 gallon tank takes up some room vertically, and a 40 or 50 or 60 gal tank would be easier to deal with. When you speak of the boiler not being able to maintain 180, who cares. If it would only keep the boiler at 150, who cares. Unless you are extremely close to design limit you will be fine. An indirect would be the ticket, however don't overlook a K-6 upgrade for long term benefits. This reinforces the assumption that bigger is better for unknown future requirements. The new electric tanks are extremely efficient and not too costly.

Look around on C-list or local papers for someone selling a 40 gallon indirect. I found a 53 gallon Buderus , three years old, for $300 this week. 1600 new.......the home had a new solar 120 gallon special tank installed, and I got it from the solar company. 1" feeds and returns, and 1" boiler feed and return. S KAA 2 would not like that flow requirement, but you could go with 3/4".
By the way, the solar tank was 5500.00, so before you jump off the solar cliff remember that was just the TANK, not the collector panels, piping, and installation. 18,000 more........but a 30% tax credit.......WTF. That was not the end of the story however........a new $32,500 auto feed pellet boiler , 6 ton hopper.......auto ash removal////all the toys.
The solar would make up 60% of the hot water needs for the year, so the original Propane Condensing Boiler will be a Primary/Secondary with the new Froling Pellet Boiler.

I asked to see the install because this is a top of the line system at over 60K, turnkey. I was certainly impressed with the logic, workmanship and the design intent....but sticker shocked at the investment. Makes upsizing the KAA seem like child's play. :shock: :?: :!: :idea:

Re: Going to Need More Hot Water...

Posted: Sat. Apr. 26, 2014 10:57 pm
by oliver power
Lightning wrote:Why not have a thermo syphon temper tank with the coal boiler water coil to preheat water in series with an electric hot water tank? Best of both worlds and with minimum demand on the coal boiler...

Edit. - and you would have the option to not use the coal boiler in the summer this way...
I like that Lightning!!! After all, I'm not using my tank-less coil. If she used the tub once per day, the tank would surly recover within 24 hours using thermo-syphon method. Thanks for your input, Oliver

Re: Going to Need More Hot Water...

Posted: Sun. Apr. 27, 2014 7:29 am
by Rob R.
oliver power wrote:
Lightning wrote:Why not have a thermo syphon temper tank with the coal boiler water coil to preheat water in series with an electric hot water tank? Best of both worlds and with minimum demand on the coal boiler...

Edit. - and you would have the option to not use the coal boiler in the summer this way...
I like that Lightning!!! After all, I'm not using my tank-less coil. If she used the tub once per day, the tank would surly recover within 24 hours using thermo-syphon method. Thanks for your input, Oliver
I thought I suggested that in the third post? :) Actually I suggest recirculation via a small circulator. Gravity circulation would work, but unless you had the power shutoff to the tank the elements would still turn on...and if the power is off, you run the risk of exhausting the hot water. A small pump could be adjusted to put a moderate load on the boiler.

Many people discover that they don't use large tubs as much as they expected, I hope you get the $ out of yours.

Re: Going to Need More Hot Water...

Posted: Sun. Apr. 27, 2014 8:29 am
by Lightning
oliver power wrote: If she used the tub once per day, the tank would surly recover within 24 hours using thermo-syphon method. Thanks for your input, Oliver
Your welcome partner. This is how I have mine set up. The difference being that I have a furnace with a water coil in the fire box instead of a boiler. I'm very pleased with its performance. I put valves in place to bypass the temper tank in the summer. So at the beginning and end of the season its just turning a few valves to send water to and from the temper tank again. The temper tank gains BTUs slowly over time thru the thermo siphon. Then, whenever hot water is used in the house that preheated water moves to the electric tank where the electric tank has the choice to heat it more if needed. Long story short, it takes a huge demand off the electric tank to produce hot water but hardly has any demand on the furnace since its a slow gain of heat...

Heres more on my set up if ya would like to see. :)

Hot Water Coil Project