HWT vs Tankless *New house*

Mukiwa · 11-30-18, 10:37 AM

We are currently building a new house and I am trying to decide between a HWT and Tankless unit.

It is 2800 sq ft double story with a 4" concrete floor built on top of 3.5" of rigid insulation with 18" of 3.5" insulation around the foundation down to the footings. We ran 6 250' runs of pex thru the floor as we want the option to heat with a boiler in the future. We have a PE Summit wood stove which will be the main heat source with propane furnace as backup so we will most likely just be keeping the slab slightly warm with the hot water not heating the whole house.

Originally I was told my best bet was to go with a Navien Combi unit but I just found out its like $4500 up here in Canada. The thing im wondering is how much more efficient the tankless units are and is it worth spending that much money when I can get a propane tank heater for $1200. I've been doing some reading and apparently the insane efficiency claims with the tankless units are only when using a small amount of hot water per day and when you get to a higher usage they start to equal out... I was told I would need a tank heater with at least 50,000 btu's but how do you do the math to figure out how much hot water you will need for your house and then decide how you will heat the water?

*another reason we would like to instal a hwt is the possibility of using the wood stove to heat the water down the road...

TIA

pinballlooking · 11-30-18, 03:40 PM

I installed a Tankless natural gas one Takagi T-H3-DV .95 energy factor
T-H3-DV-N - 199,000 BTU Natural Gas Indoor Condensing Ultra-Low NOx

https://ecorenovator.org/forum/renov...er-heater.html

We have been very happy with it. Most months we use 9 ccf
There is four of us living here.

Mukiwa · 11-30-18, 04:08 PM

Quote:

Originally Posted by pinballlooking

I installed a Tankless natural gas one Takagi T-H3-DV .95 energy factor
T-H3-DV-N - 199,000 BTU Natural Gas Indoor Condensing Ultra-Low NOx

https://ecorenovator.org/forum/renov...er-heater.html

We have been very happy with it. Most months we use 9 ccf
There is four of us living here.

It mentions a primary and secondary heat exchanges so is this a combination unit that will keep my heating and domestic how water separate? How much did this unit cost you?

Thanks

pinballlooking · 11-30-18, 04:48 PM

It has 2 heat exchanges so it can vent with PVC pipe.
The keeps venting very cheap.

It will only do one or the other. I just use it for domestic.

I paid $1,096.16 shipped with isolation valve kit.

11-30-18, 10:37 AM	#1
Mukiwa Lurking Renovator Join Date: Sep 2015 Location: BC Posts: 16 Thanks: 2 Thanked 0 Times in 0 Posts	HWT vs Tankless New house We are currently building a new house and I am trying to decide between a HWT and Tankless unit. It is 2800 sq ft double story with a 4" concrete floor built on top of 3.5" of rigid insulation with 18" of 3.5" insulation around the foundation down to the footings. We ran 6 250' runs of pex thru the floor as we want the option to heat with a boiler in the future. We have a PE Summit wood stove which will be the main heat source with propane furnace as backup so we will most likely just be keeping the slab slightly warm with the hot water not heating the whole house. Originally I was told my best bet was to go with a Navien Combi unit but I just found out its like $4500 up here in Canada. The thing im wondering is how much more efficient the tankless units are and is it worth spending that much money when I can get a propane tank heater for $1200. I've been doing some reading and apparently the insane efficiency claims with the tankless units are only when using a small amount of hot water per day and when you get to a higher usage they start to equal out... I was told I would need a tank heater with at least 50,000 btu's but how do you do the math to figure out how much hot water you will need for your house and then decide how you will heat the water? *another reason we would like to instal a hwt is the possibility of using the wood stove to heat the water down the road... TIA

11-30-18, 03:40 PM	#2
pinballlooking Super Moderator Join Date: Jun 2013 Location: SC Posts: 2,923 Thanks: 172 Thanked 564 Times in 463 Posts	I installed a Tankless natural gas one Takagi T-H3-DV .95 energy factor T-H3-DV-N - 199,000 BTU Natural Gas Indoor Condensing Ultra-Low NOx https://ecorenovator.org/forum/renov...er-heater.html We have been very happy with it. Most months we use 9 ccf There is four of us living here. __________________ Current project Aquaponics system , Passive Solar Greenhouse build To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Solar Install 12.5 Kwh- To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Mini Split installs - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. EV Chevy Volt - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.

11-30-18, 04:48 PM	#4
pinballlooking Super Moderator Join Date: Jun 2013 Location: SC Posts: 2,923 Thanks: 172 Thanked 564 Times in 463 Posts	It has 2 heat exchanges so it can vent with PVC pipe. The keeps venting very cheap. It will only do one or the other. I just use it for domestic. I paid $1,096.16 shipped with isolation valve kit. __________________ Current project Aquaponics system , Passive Solar Greenhouse build To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Solar Install 12.5 Kwh- To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. Mini Split installs - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts. EV Chevy Volt - To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.