Kuuma Installation Question

[DaveH]

I couldn't agree with you more. My HPHW costs me about one-fourth of what it cost me to run my Marathon.


Have you looked at Marathon ? They are plastic and have a lifetime tank warranty.

After researching HPHW I think I'm sold on them. I wish some of the less expensive models had better reviews, but the Stiebel Eltron seems to be the only bullet proof model. The GE model has had problems it seems, that may or may not have been worked out. There is a $400 rebate in Upstate NY from the power company, so that helps take the sting off. The 80 gallon model is sold at home depot, but I cant find where to by the smaller unit.

 

[sloeffle]

I got an AO Smith Voltex 50 gallon for the same price they are selling the GE's HPHW here in Ohio for. The AO Smith has a 10 year warranty. @woodgeek has had the 80 gallon model for a few years without that many issues from what I can recall.

 

[brant2000]

The build up causes the issues. You'll get build up under that seat, and it won't reseal. Thats also a pretty bad / dangerous habit to be manipulating a T/P valve.

Respectfully, I'm not sure that I agree. Just like is done with high pressure boilers, I think it's a good practice to exercise relief valves. Otherwise, they may not work when they need to.

 

[STIHLY DAN]

After researching HPHW I think I'm sold on them. I wish some of the less expensive models had better reviews, but the Stiebel Eltron seems to be the only bullet proof model. The GE model has had problems it seems, that may or may not have been worked out. There is a $400 rebate in Upstate NY from the power company, so that helps take the sting off. The 80 gallon model is sold at home depot, but I cant find where to by the smaller unit.

They fixed all the GE problems with the manufacturing moved to the us. Have had mine for 3 years and no issues. They also have a 10 year warranty. If you can fit and afford an 80 gal go with that.

 

[DaveH]

They fixed all the GE problems with the manufacturing moved to the us. Have had mine for 3 years and no issues. They also have a 10 year warranty. If you can fit and afford an 80 gal go with that.

Do you use the H2O coil on the Kuuma? I spoke to Steibel Eltron rep about using pre heated water with the HPWH and they said it isn't preferred. I'd guess the savings would be bigger not using the $200 coil (if I couldnt use it), and buying a HPWH then using the coil and a traditional water heater.

I heard the GE problems were caused by Chinese manufacturing. Good to hear they moved it here. They are an option for me.

Chimney going up tomorrow, then I can start hook up of duct work and electrical.

 

[STIHLY DAN]

I do have the coil on mine. I use an 80 gal unplugged electric water heater as a tempering tank, that feeds the hpwh.

 

[DaveH]

I do have the coil on mine. I use an 80 gal unplugged electric water heater as a tempering tank, that feeds the hpwh.

Thanks. Steibel Eltron rep said cold water at the bottom of the tank helps the R134 refrigerant turn from a hot gas back into a liquid to restart the process. If it works for you i might give it a try.

 

[DaveH]

Chimney is in. Furnace is in place. Duct work scheduled. My concern now is again hot water. Installer is questioning the use of a tempering tank. He wants to hook the H2O coil right up to the current water heater. I am likely getting the tank but will either way work?

 

[STIHLY DAN]

Its hard to heat hot water when its already hot. Greater the temp difference, better the heat transfer.

 

[DaveH]

 

[JRHAWK9]

Installer is questioning the use of a tempering tank. He wants to hook the H2O coil right up to the current water heater. I am likely getting the tank but will either way work?

Last summer when I installed my Kuuma a local plumber was also looking at me sideways when telling him how I wanted the old 40 gal electric water heater I had connected between my coil and water heater...lol I decided to do it all myself. Saved a lot of $$ as well.

 

[brenndatomu]

Looks good. What size is you return air duct there...looks like a single 8"?
EDIT: Never mind, I just seen the second pic, 12" pipe?

 

[begreen]

The ducting looks undersized. The VaporFire 100 has a 24x24" supply plenum. Looks like it is being restricted quite a bit. Supply looks to be about 8" x 24" or 192 sq in. The return if 12" round is about a fifth of the supply plenum size and much smaller than the supply duct. Restrict it too much and the blower may race due to too much static pressure. Also, this could be problematic during a power outage:
DUCTS SHOULD BE LARGE ENOUGH TO HANDLE GRAVITY AIRFLOW IN EVENT OF ELECTRIC POWER OR FURNACE FAN FAILURE (APPROXIMATELY180-200 SQ. IN.)

 

[STIHLY DAN]

A few suggestions and questions. I agree with BEGREEN on the duct looking a bit undersized. Are there backdraft dampers installed? Also on the flue pipe you may want 1 45 and 1 90 instead of the 3 90's. When you pipe in the water heater using all 45's and no 90's will help with the thermo syphon. I also highly recommend a tempering tank. You are going to by happy with this, just needs a few tweak's.

 

[DaveH]

I'll look into improving the duct work set up.

 

[maple1]

I'm not a furnace or hot air guy but I don't think that's the damper they're talking about.

I think they mean dampers in the duct work to make sure the air doesn't go opposite to the way you want, with more than one furnace in the equation?

 

[DaveH]

I'm not a furnace or hot air guy but I don't think that's the damper they're talking about.

I think they mean dampers in the duct work to make sure the air doesn't go opposite to the way you want, with more than one furnace in the equation?

yes. There are dampers installed in the duct work

 

[STIHLY DAN]

manual or auto dampers?

 

[DaveH]

manual or auto dampers?

manual dampers

 

[STIHLY DAN]

Just make sure that when the Kuuma is running that the supply is not going through your gas furnace out the return back to the Kuuma. You will get no heat and hurt the Kuuma.

 

[DaveH]

The ducting looks undersized. The VaporFire 100 has a 24x24" supply plenum. Looks like it is being restricted quite a bit. Supply looks to be about 8" x 24" or 192 sq in. The return if 12" round is about a fifth of the supply plenum size and much smaller than the supply duct. Restrict it too much and the blower may race due to too much static pressure. Also, this could be problematic during a power outage:
DUCTS SHOULD BE LARGE ENOUGH TO HANDLE GRAVITY AIRFLOW IN EVENT OF ELECTRIC POWER OR FURNACE FAN FAILURE (APPROXIMATELY180-200 SQ. IN.)

I am a little small for duct work at 160 SQ inch. All of my duct work was pre existing, so I would need a complete overhaul. I have a two story colonial, so considering the duct work in the walls aren't going to change I am limited in what i can do. I am looking into a fresh air intake that the furnace can draw off of.

As far as gravity flow during a power outage, I could replace the "stem" duct work but how much would that help if it fed to 8 by 20 duct work running vertically to the 2nd floor?

 

[DaveH]

Looks good. What size is you return air duct there...looks like a single 8"?
EDIT: Never mind, I just seen the second pic, 12" pipe?

EDIT : That is 14n. I might have to fire it up to see if it needs a fresh air intake. I half want the weather cool down so I can fire it up.

 

[maple1]

Not sure what the Kuuma specs but looks like your supply is restricted some - and your 12" return is 30% smaller than the supply. Not sure how all that will balance out since there are likely other factors involved.

 

[STIHLY DAN]

You are choked down on supply, and really choked down on return. In order to make your unit work properly you need to do something with your ductwork. That is too nice a unit to burn up on an incorrect install. Maybe hire someone and give them the installation directions.

 

[DaveH]

You are choked down on supply, and really choked down on return. In order to make your unit work properly you need to do something with your ductwork. That is too nice a unit to burn up on an incorrect install. Maybe hire someone and give them the installation directions.

The vertical return is 196 sq in. The unit was installed professionally, of course it remains a work in progress.