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Topic:   High Efficiency Water Heaters - 2373 visits (1 today, 2 this week)

Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 19, 2005 01:52 PM            

I haven't seen one of these in a while, they don't come around often. I remember the first one I ran across I thought they had a problem with venting the flue gasses. Are these high efficiency water heaters popular anywhere? Do you see many issues with the inducer fans quitting? I spoke with the homeowner and he seems to like the WH very much.
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Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 19, 2005 01:55 PM            

Oh, and I got a great laugh when I saw this one yesterday! (that is a condensing pump drain line running into it)

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Rick Hurst
Member



Posts: 3820
From:Rockwall, TX
Registered: Oct 2003

posted December 19, 2005 09:12 PM            

That CPVC is way to close to the draft hood on that water heater. I see a number of these lines that have heat damages from being in close proximity to the draft hood. It is also on the T&P valve which is not rated for.

Looks also to be some corrosion on top of the tank also.

Rick

Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 20, 2005 06:20 AM            

Rick,
I don't disagree with the CPVC being too close to the draft hood but after many searches through direct vent websites I have yet to see any clear guidelines reguarding the requirements. I suspect if I ever catch an owners manual with installation instructions I may get some information. Do you know of any references that can shed some light? Thanks

Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 20, 2005 10:12 AM            

Rick,
I missed where you said CPVC isn't rated for the TPR valve. Could you provide a source with that informatin for me? During my formal training I was taught that it was, during my working with other inspectors I was told it was, and I have always went on the pretense that it was. IRC P2803.6.1 does not specify requirements so I follow IRC P29045 (Water-distribution piping) that states ....all hot-water-distribution pipe and tubing shall have a minimum pressure rating of 100 psi at 180 degrees F....., which CPVC (that meets or exceeds the required standards) does. In fact I believe CPVC has been tested and found capable of withstanding prolonged bursts from a water heater TPRV.
If I am missing something? Thanks.

Rick Hurst
Member



Posts: 3820
From:Rockwall, TX
Registered: Oct 2003

posted December 20, 2005 11:32 PM            

The CPVC is rated for 180 degrees and the T&P valve is rated at 210 degrees. Most CPVC have this stated on the side of the material. In my opinion it is not acceptable and I call it out as a repair and recommend that a copper line be installed.

Rick

Rick Hurst
Member



Posts: 3820
From:Rockwall, TX
Registered: Oct 2003

posted December 20, 2005 11:40 PM            

Here's a link from the manufacture of CPVC which mentions that the material should be at least (6) inches from the draft hood.

Rick
http://www.charlottepipe.com/Documents/FGG_Tech_Manual/FGG_Tech_Manual%5Chtml%5CFGG_Tech_Manual_9.html

Michael Thomas
Member


Posts: 193
From:Evanston, IL
Registered: Jul 2005

posted December 21, 2005 05:19 AM            

1) That WH is intended to vent to PVC (as in that picture). Woud that design reduce temperature in the vicinity of the vent hood to below the 180°F limit for CPVC? (I realize that you cannot vent exhaust through CPVC, and that the direct connection to the HW outlet would still be wrong.)

2) What’s with all that corrosion?

[This message has been edited by Michael Thomas (edited December 21, 2005).]

David Wood
Member


Posts: 101
From:Mississauga, Ontario, Canada
Registered: Feb 2004

posted December 21, 2005 07:00 AM            

That water heater looks like it is induced draft, not high efficiency (condensing). Most new installations here are induced draft because high efficiency furnaces have become very popular - so most houses are built without a chimney. The fans become noisy and usually fail at 5-8 years. I tell my clients to expect to replace it at least once over the life of the water heater.

There is no vent hood on an induced draft appliance.

I would not be concerned about CPVC on the TPR valve. It is not under pressure and normally should not even be exposed to hot water. It is rare here to see anything else.

Chuck Lambert
Member


Posts: 157
From:Fountain Valley, CA
Registered: Sep 2001

posted December 21, 2005 07:40 AM            

UPC 608.5 allows CPVC as T&P relief line

Rick Hurst
Member



Posts: 3820
From:Rockwall, TX
Registered: Oct 2003

posted December 21, 2005 08:21 AM            

It (CPVC) may be allowed by code, but here is a company that i gave a link for stating otherwise.

Over the years, I've learned one thing as a PC operator also. You always follow product labels as they supercede all else.

As a HI I also have to use experience in the field of what I've actually seen when making recommendations.

In the last 3 years, I've seen 4 homes with CPVC on top of a gas WH have damaged lines caused from heat off the draft hood.

One that comes to mind was in a 4 mil. home located in an attic which melted and ran water for 2 days and caused over 150K dollars worth of damages.

I also know of a municipality in our inspection area that used to allow CPVC but has reversed its requirement back to the use of copper.

So any of you may wish to say its acceptable on your reports, thats ok, but on mine I recommend the lines be replaced with copper.

Just my opinion

Rick

David Wood
Member


Posts: 101
From:Mississauga, Ontario, Canada
Registered: Feb 2004

posted December 21, 2005 09:54 AM            

Interesting how things are done differently in different regions. Around here the water heater is always in the basement and the TP valve discharges onto the floor. CPVC does just as good a job at dumping water on the floor as anything else.

I can see how you would look at it entirely differently if it was located in the attic of a $4M house.

Chuck Lambert
Member


Posts: 157
From:Fountain Valley, CA
Registered: Sep 2001

posted December 21, 2005 02:46 PM            

Did not say I agreed with it, just that it is allowed.

Chuck

RANDY NICHOLAS
Member


Posts: 64
From:MANSFIELD, TEXAS
Registered: Dec 2003

posted December 21, 2005 07:20 PM            

DAVID, IF THAT'S THE CASE IN CANADA, WHY DO YOU EVEN NEED THE T&P TO BE PIPED?? "LET 'ER RIP" AND "LOOK OUT BUBBA WE'RE GONNA GIT HOT WATER" "MAMA GIT THE MOP"

Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 21, 2005 07:32 PM            

Ok, got it. I rarely see anything other than CPVC in this area. Maybe copper occasionally, black pipe, sometimes nothing (i.e., let err ripppp) but mostly CPVC. It was a high efficiency heater, but why the draft hood? Didn't really consider it necessary to investigate. Next time I will and will follow up with the few others that I have come across. We are poor in this neck-o-the-woods so they don't come along often. But considering all these issues with the TPRV I think I'm just taking the thing off and capping the hole on mine!
Thanks for the info.

David Wood
Member


Posts: 101
From:Mississauga, Ontario, Canada
Registered: Feb 2004

posted December 22, 2005 08:43 AM            

Randy,

The TP valve is piped so the water doesn't hit you in the face when it blows. It is not allowed to be plumbed into a drain. It must be impossible for it to be blocked. I don't see how the occasional shot of hot water is going to damage a CPVC pipe or impede its function in any way, because by design it never sees any pressure.

And here in Canada, its not Bubba, its Bob and Doug eh?

Jerry Peck
Member




Posts: 7925
From:Pembroke Pines, FL
Registered: Feb 2003

posted December 22, 2005 09:05 AM            

"I don't see how the occasional shot of hot water is going to damage a CPVC pipe or impede its function in any way, because by design it never sees any pressure."

Actually, T&P drain lines do see some (but not much) pressure under full release. Just not enough to cause any concern at all, as long as the end is not restricted.

CPVC is has been tested and found suitable for use as T&P drain lines as the high temperature is only short duration, being cooled by the incoming cold water supply as the T&P dumps water out, being cooled sufficiently enough and quick enough to drop the temperature down to within its range.

Now, placing CPVC THAT CLOSE to the heat-producing vent ... ?

Those pressure and temperature rating on CPVC are its maximum operating pressure and temperature for the water inside it, NOT for its ambient temperature outside next to it.

------------------
Jerry Peck
South Florida

Craig Martin
Member


Posts: 65
From:East Dundee, IL
Registered: Feb 2005

posted December 22, 2005 03:17 PM            

"The TP valve is piped so the water doesn't hit you in the face when it blows."

That's the sole reason the extension is required. So that someone standing near the heater doesn't get third degree burns and melted eyeballs.

Many areas around here don't allow "Non-metallic" extensions on TPR valves. I see mostly copper, then galvanized, and the ocassional threaded end (sometimes, even with a cap on it!). Usually the new heaters have the CPVC pipes - I replaced mine with copper, but the heater came with a CPVC pipe.

Craig Martin
East Dundee, IL

Jim Vaughn
Member


Posts: 77
From:ARLINGTON VA
Registered: Jan 2001

posted December 24, 2005 03:45 PM            

Michael - you asked why the draft inducer? Usually because there is no available gas flue.
As for removing the TPR and plugging the hole, you better hope NOTHING ever goes wrong with the water heater. Steam has a lot of force - a water heater gone bad can take a lot with it!

Michael Greenwalt
Member


Posts: 26
From:Milford KS
Registered: Sep 2005

posted December 27, 2005 02:55 PM            

Actually, I was kidding about plugging the hole. No need for an explosive in the ol homestead!

Bob Knauff
Member



Posts: 1298
From:MN
Registered: May 2002

posted December 28, 2005 08:44 AM            

As in Davids part of the world nearly 100% of our heaters are in basements also. TPRs are simply allowed to discharge to the floor within 16" - 18" but a floor drain needs to be nearby to prevent flooding. Typically the floor drain also accepts A/C condensate as well as 90% furnace condensate and maybe dehumidifier discharge or humidifier overflow plus the water softener discharge, it's not there just for a water heater discharge.

------------------
Bob

Think Safety!

www.BeaconHomeInspections.com

Proudly serving the Twin Cities and areas surrounding Minneapolis and St. Paul in Minnesota

[This message has been edited by Bob Knauff (edited December 28, 2005).]

mark weilhammer
Member


Posts: 62
From:indianapolis , ind
Registered: Aug 2004

posted December 30, 2005 03:04 PM            

this is a common power vent water heater

loooks like a Rheem unit, nothing special about it , at least in the mid-west....

the t+p overflow con go either way either sopper or cpvc, depending on where you are in the usa

Dan Cullen
Member


Posts: 51
From:Chicago IL
Registered: Dec 2005

posted December 31, 2005 07:52 AM            

Hi Mike....one thing that can cause issues with the power vented WH's is too many elbows (esp. 90's) and overly long vent runs. This can cause back pressure on the flue gas and cause the unit to shut down, sometimes intermittently. The mfr. specs the max. # and degree of bends and overall piping length.

An open question here; isn't the purpose of the power vent to pull the gases through a somewhat convoluted heat exchanger path inside the unit that works to increase the amount of heat energy imparted to the water tank?

David Wood
Member


Posts: 101
From:Mississauga, Ontario, Canada
Registered: Feb 2004

posted December 31, 2005 11:40 AM            

We model an induced draft water heater at 57% seasonal efficiency and a natural draft at 55% when we do energy audits. These are the numbers that Natural Resources Canada has approved for use in their energy efficiency modeling software. So yes, an induced draft heater has slightly better effciency, but the main purpose of the fan is to get the exhaust gases out of the house without using a chimney.

Dan Cullen
Member


Posts: 51
From:Chicago IL
Registered: Dec 2005

posted December 31, 2005 07:00 PM            

hey dave...isn't any gas appliance that vents through PVC technically high efficiency?

David Wood
Member


Posts: 101
From:Mississauga, Ontario, Canada
Registered: Feb 2004

posted January 01, 2006 08:23 AM            

Dan,

No, a PVC vent does not necessarily mean high efficiency. To be considered high efficiency, the exhaust gasses must be condensed. The condensing recovers the latent heat of vaporization and brings the steady state efficiency from the low 80's to over 90%.

Induced draft water heaters take enough energy out of the exhaust to allow the use of plastic venting, but they do not condense the exhaust. As far as I know there are only 2 consensing water heaters, the Lennox Complete Heat(no longer made) and the Polaris. They are almost always used in combination systems (water heater heats the house and provides domestic hot water).

Dan Cullen
Member


Posts: 51
From:Chicago IL
Registered: Dec 2005

posted January 01, 2006 02:17 PM            

thanks again dave...what is the definition of 'condensing' as you use it to determine the efficiency rating? Do you mean that there has to be a condensate drain somewhere on the w.h. unit?