Dave Turpin
14th May 2012, 22:44
As promised, please allow me to share some pictures and lessons learned with the installation of a Rinnai Condensing tankless water heater and hydronic furnace.
Background: I wanted to remove the clunker of an old gas furnace and the old 50-gallon tank water heater. The water heater still had a pilot light! That's how old it was.
I did not want to spend my life savings, but I found that DIY is not only feasible, but LEGAL, at least in my area.
List of parts:
-Rinnai RC98i tankless water heater. 199,000 BTU/hr, 96% thermally efficient (0.94 EF), capable of 9.8 GPM of flow at 50F rise in temp.
-Coaxial exhaust plumbing, specifically for Rinnai condensing units. 2-45's, 7-30" pieces, roof cap.
-Rinnai 75,000 BTU/hr hydronic air handler. Rated at this heat transfer rate with 150F hot water and 50F rise in air temp.
-Whole house air cleaner and electrostatic precipitator
-Various HVAC plumbing
-Various valving, plumbing, thermostatic valve, air seperator
-Screws, tape, various PVC parts to make condensate Neutralizer
Total cost including little bits: $5120.
Total cost if you wanted a plumber to install it: Don't know. A lot.
EDIT: Forgot to mention. Puget Sound Energy gave me a $800 rebate for installing this bad boy. So the net cost to me was only $4320. You might ask, "what is the payback period for this?" There are a couple ways to look at it. One, if I somehow manage to cut my gas use in half, I will save about $720 a year. So in less than a decade it will pay for itself. But the real answer is: Immediately! Assuming that I intend to sell the house, installing a brand new high efficiency water heater and furnace will more than pay for itself in the sale price. (As a rule of thumb, no buyer will pay extra for a high efficiency water heater, but they also cannot "demand" money off to replace an old furnace, either. I actually talked the seller down $10,000 to deal with the old furnace and heater... So I am already $5680 ahead of the game)
I don't have all the pictures of the step-by-step, but here are some of the major ones.
After cutting out the old water heater, here is the mounting of the new one:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012183.jpg
As you can see, I had to plumb in new gas line. This is where the gas inspection came in. Not as easy as replacing a tank heater with another tank heater! However I did not have trouble with leaks. Lesson learned, though: The proper way to test the gas is:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012188.jpg
Instead of an elbow coming into the heater, use a tee, and add an extra length that you can connect a gas gauge to. (These gas gauges are available at Home Depot, etc) The gas is off of course. Unscrew the outlet from the gas meter, and plug it. I found it easiest to remove the connector entirely and just threaded a plug into the gas line. Shut any valves to other appliances. Then pump up with a bike pump. If it doesn't hold pressure at 10 psi for several hours, you may have a leak. After you pass inspection, remove the gauge and cap it, then reattach the gas line to the meter, turn the gas on, and soap bubble test the cap and meter.
Of course, you need to provide power for the water heater, off a GFCI line. I wired one in (don't tell anyone that I did the wiring myself... As well as the wiring for my entire house)
Before I finished the plumbing, though, I took out this:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012182.jpg
And put in this:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012186.jpg
Follow the diagram for plumbing that comes with the handler. The simplest explanation is that lines tee off of the cold and hot water lines from the tankless hot water heater.
Lesson learned 2: The tankless water heater can only produce one temperature! In order to work efficiently, you need to turn the hot water heater up all the way (140F is the highest you can get with the factory-installed temperature controller, and only after overriding a setting in the heater) This means the air handler can only produce about 72000 BTU/hr (my calculations), and you MUST use a tempering valve to cool the DHW to a safe temperature. In these pictures I had not yet installed this valve.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012185.jpg
There I am cramped in my mechanical room with not enough light.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012190.jpg
There is the plumbing for the air handler going in.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012189.jpg
Reconstructing the HVAC plenums. Some would consider this the hard part. I had to make some custom pieces to make it all fit with the old air ducting, and in some cases I redirected ducting to improve balance. I happen to be a Mechanical Engineer. (Although my specialty is Naval Architecture, believe it or not)
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012187.jpg
And there is the all-plumbed-up view. Again, without the tempering valve. You will see that I added a new expansion tank, the exhaust, etc.
A note on the exhaust: I only used so much because I wanted to reuse my furnace chimney. There are probably easier ways to do this. It was a serious PITA and my wife had to help as I lowered the pieces from the roof.
Conclusion:
So far so good. I can actually heat the house while taking a shower, having a guest use another shower and running laundry. My only limitation is how much water I can get in to the house from the service! That is the next and final plumbing task to tackle.
Background: I wanted to remove the clunker of an old gas furnace and the old 50-gallon tank water heater. The water heater still had a pilot light! That's how old it was.
I did not want to spend my life savings, but I found that DIY is not only feasible, but LEGAL, at least in my area.
List of parts:
-Rinnai RC98i tankless water heater. 199,000 BTU/hr, 96% thermally efficient (0.94 EF), capable of 9.8 GPM of flow at 50F rise in temp.
-Coaxial exhaust plumbing, specifically for Rinnai condensing units. 2-45's, 7-30" pieces, roof cap.
-Rinnai 75,000 BTU/hr hydronic air handler. Rated at this heat transfer rate with 150F hot water and 50F rise in air temp.
-Whole house air cleaner and electrostatic precipitator
-Various HVAC plumbing
-Various valving, plumbing, thermostatic valve, air seperator
-Screws, tape, various PVC parts to make condensate Neutralizer
Total cost including little bits: $5120.
Total cost if you wanted a plumber to install it: Don't know. A lot.
EDIT: Forgot to mention. Puget Sound Energy gave me a $800 rebate for installing this bad boy. So the net cost to me was only $4320. You might ask, "what is the payback period for this?" There are a couple ways to look at it. One, if I somehow manage to cut my gas use in half, I will save about $720 a year. So in less than a decade it will pay for itself. But the real answer is: Immediately! Assuming that I intend to sell the house, installing a brand new high efficiency water heater and furnace will more than pay for itself in the sale price. (As a rule of thumb, no buyer will pay extra for a high efficiency water heater, but they also cannot "demand" money off to replace an old furnace, either. I actually talked the seller down $10,000 to deal with the old furnace and heater... So I am already $5680 ahead of the game)
I don't have all the pictures of the step-by-step, but here are some of the major ones.
After cutting out the old water heater, here is the mounting of the new one:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012183.jpg
As you can see, I had to plumb in new gas line. This is where the gas inspection came in. Not as easy as replacing a tank heater with another tank heater! However I did not have trouble with leaks. Lesson learned, though: The proper way to test the gas is:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012188.jpg
Instead of an elbow coming into the heater, use a tee, and add an extra length that you can connect a gas gauge to. (These gas gauges are available at Home Depot, etc) The gas is off of course. Unscrew the outlet from the gas meter, and plug it. I found it easiest to remove the connector entirely and just threaded a plug into the gas line. Shut any valves to other appliances. Then pump up with a bike pump. If it doesn't hold pressure at 10 psi for several hours, you may have a leak. After you pass inspection, remove the gauge and cap it, then reattach the gas line to the meter, turn the gas on, and soap bubble test the cap and meter.
Of course, you need to provide power for the water heater, off a GFCI line. I wired one in (don't tell anyone that I did the wiring myself... As well as the wiring for my entire house)
Before I finished the plumbing, though, I took out this:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012182.jpg
And put in this:
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012186.jpg
Follow the diagram for plumbing that comes with the handler. The simplest explanation is that lines tee off of the cold and hot water lines from the tankless hot water heater.
Lesson learned 2: The tankless water heater can only produce one temperature! In order to work efficiently, you need to turn the hot water heater up all the way (140F is the highest you can get with the factory-installed temperature controller, and only after overriding a setting in the heater) This means the air handler can only produce about 72000 BTU/hr (my calculations), and you MUST use a tempering valve to cool the DHW to a safe temperature. In these pictures I had not yet installed this valve.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012185.jpg
There I am cramped in my mechanical room with not enough light.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012190.jpg
There is the plumbing for the air handler going in.
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012189.jpg
Reconstructing the HVAC plenums. Some would consider this the hard part. I had to make some custom pieces to make it all fit with the old air ducting, and in some cases I redirected ducting to improve balance. I happen to be a Mechanical Engineer. (Although my specialty is Naval Architecture, believe it or not)
http://i207.photobucket.com/albums/bb21/bpestilence/AprilandMay2012187.jpg
And there is the all-plumbed-up view. Again, without the tempering valve. You will see that I added a new expansion tank, the exhaust, etc.
A note on the exhaust: I only used so much because I wanted to reuse my furnace chimney. There are probably easier ways to do this. It was a serious PITA and my wife had to help as I lowered the pieces from the roof.
Conclusion:
So far so good. I can actually heat the house while taking a shower, having a guest use another shower and running laundry. My only limitation is how much water I can get in to the house from the service! That is the next and final plumbing task to tackle.