Resistance of thermal switch in thermocouple - does it matter - hot water heater - generic replacement

Page 1 of 2  
Does the difference in resistance matter if you replace a 24-inch 30mv thermocouple that has a thermal switch versus one without the thermal switch?
http://i.cubeupload.com/xqThcA.jpg
I bought a generic Honeywell 30mv 24-inch thermocuple (PN CQ100A1013) from Ace Hardware: http://www.acehardware.com/product/index.jsp?productId 877505
That picture in the URL above is wrong because it's 24 inches: https://www.amazon.com/Honeywell-CQ100A1013-Replacement-Thermocouple-Furnaces/dp/B000BPHNW2#productDetails
When I went to put it in the hot water heater, I belatedly realized the original thermocouple has an integral thermal switch.
http://i.cubeupload.com/TtyF4c.jpg
I know the length matters, from a resistance standpoint, but the hardware store owner had never heard of a thermocouple with at thermal switch before:
http://i.cubeupload.com/z1862F.jpg
The thermal switch is a safety feature that will shut down the pilot if the heat under the hot water heater gets too great:
http://i.cubeupload.com/Qh4PMI.jpg
When I call Sears in San Jose at 408-274-2593, they confirm the part number is PN 9000056015 but that replacement part doesn't seem to have a thermal switch on it. http://www.supplyhouse.com/AO-Smith-9000056015-Thermocouple-Kit-Model-TC-K24 https://www.heritageparts.com/Napa-Technology/Manufacturers/A-O-Smith/A-O-SMITH-THERMOCOUPLE/p/AOS9000056015 http://www.jupiterheating.com/ao-smith/parts/9000056015.html http://www.terapeak.com/worth/new-state-a-o-smith-9000056015-thermocouple-kit-model-tc-k24/230984311909/
Have you ever had to make the decision of whether to replace a thermocouple that had a built-in thermal switch with a generic thermocouple that had no thermal switch? Did the resistance match?
http://i.cubeupload.com/nFG8Ip.jpg
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, August 19, 2016 at 7:16:55 PM UTC-4, Danny D. wrote:

I'd say the resistance doesn't matter because there probably is no material difference in resistance. But without the thermal fuse, whatever safety that it provides is gone. In other words, it should work, but without the additional feature. Does it? I guess the question comes down to is what you wind up with the same as my WH and most others that don't have this or does my WH and others have some other way of thermal cut off instead that yours doesn't have, thereby leaving yours unsafe? IDK
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Fri, 19 Aug 2016 16:33:50 -0700 (PDT), trader_4 wrote:

IDK either.
The book resistance of the Honeywell CQ100A1013 thermocouple is apparently 0.2 ohms but that's all I could find out by way of technical specs from either Sears or from Honeywell.
Sears confirmed the replacement part number is 9000056015, but when I look up *that* part number, none of the pictures show the thermal switch.
The fit of the Honeywell CQ100A1013 "universal" thermocouple isn't even close to the same as the original fit either as the mounting for the original is screwed on with a plate while the "universal" Honeywell thermocouple is a screw on nut which doesn't have a corresponding mating female.
Therefore, the "universal" thermocouple isn't even close to universal, although I can probably bend some metal to make it fit - I'm basically making my own parts out of raw materials.
When I called Honeywell technical support at 800-468-1502x1x1x9x1 to find out if they have a closer replacement than the Honeywell CQ100A1013 that I bought, they drove me nuts in so much as they don't even understand the simplest thing about the product they sell.
All they could tell me is that it has to go 1/2 inch into the flame.
When I asked for a thermocouople with a theroswitch, they told me to use the Q340A1074 but that doesn't seem to have a thermoswitch either. https://www.amazon.com/Honeywell-Q340A1074-International-Thermocouple/dp/B00E0CWKPC
So I'm basically making my own parts from raw materials because the mounts aren't even close on *any* of these so-called replacement thermocouples.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 20 Aug 2016 01:21:37 +0000 (UTC), Danny D. wrote:

I concluded the "universal" mount stood zero chance of fitting.
http://i.cubeupload.com/mYJNjq.jpg
There is just no way a "universal" thermocouple is going to stay put there.
http://i.cubeupload.com/8G0mAF.jpg
Just look at this bracket for my original thermocouple.
http://i.cubeupload.com/vQVXGL.jpg
For now, I sandpapered the thermocouple and put it back in, but I think I'll either have to find an exact replacement or build my own bracket assembly.
I can't believe everyone runs into this fit problem. Do you?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 8/20/16 12:13 AM, Danny D. wrote:

According to this A O Smith webpage, see page 18 at http://www.hotwater.com/lit/training/320991-000.pdf
"the thermocouple is not a separate replaceable part."
"There is no routine service associated with the TCO"
"The TCO is an integral part of the thermocouple and not replaceable as a separate item. A pilot burner assembly must be reinstalled."
See picture and instructions on page 20
Not knowing your specific model & serial numbers, 2 possible parts are shown at https://www.wallingfordsales.com/products.asp?catV4&pgh P/N's 9006013005 or 9006014005
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Saturday, August 20, 2016 at 8:24:15 AM UTC-4, Retired wrote:

You left out the best part. One of those is $117, the other $144!
Doh!
What's a regular TC cost? $15? Looks like they changed a design from a cheap, common TC to this thing that costs 10X. How much additional protection it provides, is it really necessary and/or worth it, IDK. All I know is they were making WHs for how many decades with the old style and I didn't see any widespread carnage. I thought the biggest issue was either blocked flues generating CO or idiots using gasoline or similar solvents in close proximity.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 20 Aug 2016 06:04:33 -0700 (PDT), trader_4 wrote:

After calling the AO Smith residential support phone number at 800-527-1953, I found, after giving the nice lady my serial number, that the part number I need is the $88 MSRP pilot assembly P/N 9003455005.
Unlike cars, I have found out that MSRP is generally *lower* from the manufacturer than the parts suppliers in San Jose, so I expect it to cost more if sourced locally.
Even so, I called the dealers she suggested, only one of which was open on a weekend, who himself, no longer sells AO Smith parts. So I'll have to wait for the weekend to find price and availability at local sources.
Googling, the pilot assembly seems to be a whole bunch of stuff: http://www.hvac.com/shop/ao-smith-9003455005-kit-fv-pilot-180-deg-c-lp
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
trader_4 posted for all of us...

Thank government regulation.
--
Tekkie

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sat, 20 Aug 2016 16:59:13 -0400, Tekkie? wrote:

Just to report back, the sandpapered thermocouple has been working, so I have time to order the correct parts, probably from AO Smith themselves as they have an order number for parts:
When I buy the pilot assembly, should I buy an anode?
I have hard water (calcium carbonate rich). How often do you replace your anodes?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, August 22, 2016 at 12:40:55 PM UTC-4, Danny D. wrote:

s

I don't. There are two competing theories on this. One is that replacing it will extend the life. The other is that the tank is still going to fail at about the same time from other effects anyway. If you want to replace it pull the old one part way out to see how much is left, do that every few years to keep an eye on it. I just went the lazy route. So far, about 15 years on a garden variety State.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Danny D. posted for all of us...

s

I don't have that type heater. You may want to see if you can get the anode out. Might be a problem. I think I would procure the anode locally as I think shipping may be expensive.
--
Tekkie

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 22 Aug 2016 16:07:20 -0400, Tekkie? wrote:

You have a point on the shipping, as the anode is long I presume. Mine has the hot-water nipple on the end also.
I checked three parts stores. None had it in stock while most had the pilot assembly in stock.
So, people replace the AO Smith pilot assembly more so than they do the anode (or they use a different anode part number).
- pilot assembly 9003455005 $88 - anode with nipple 9009148005 $38
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

*If* you can remove it; there's very little of the aluminum or magnesium rod still left, and you can see the supporting wires.
You should be checking the anode every year or two, this also keeps it from corroding in place, so you *can* check it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Also, IIRC, it uses a large socket (1-1/8"?) and a long 1/2 drive breaker bar . They are usually very very tight. Just drain a little water out (gallon or so) and still you may need an extra hand to hold on to the tank. You will need some clearance above the tank to put the rod in.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Monday, August 22, 2016 at 4:39:55 PM UTC-4, tom wrote:

They sell new ones that are in sections for people who have that problem.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 22 Aug 2016 16:26:25 -0700 (PDT), trader_4 wrote:

Thank you for bringing the vertical space up as a problem, as I might have that problem since the hot water heater is in a relatively small closet, and it's on a pedestal off the ground.
I never thought of that problem until you mentioned it.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I removed mine when the tank was about 5 years old. It took a large pipe wrench (the hex top of the rod was above the tank) and a 3 foot or so section of galvanized pipe on the wrench handle and lots of effort to remove it.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tue, 23 Aug 2016 20:08:45 -0000 (UTC), Jerry Peters wrote:

I had a spare hot water tank to practice on and it was 27mm and it took a very long pipe (about 8 feet) to twist it off.
So, those things are in there rather well if they're not removed every once in a while!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Mon, 22 Aug 2016 20:19:12 -0000 (UTC), Jerry Peters wrote:

This makes a lot of sense to remove the anode yearly so that you can remove it before it corrodes in place.
Unfortunately for me, the AO Smith anode (PN 9009148005) comes with the hot-water nipple, so, they have it inline (somehow) with the hot water pipe.
Seems silly to me that I have to basically disconnect the water pipes just to check the anode.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Tuesday, August 23, 2016 at 8:12:40 AM UTC-4, Danny D. wrote:

Between that thermal fuse at the burner and the screwy anode that's part of the water pipe connection, I've heard enough to stay away from AO Smith. It looks to me that they are doing things in a way to force you into parts that you can only get from them. Bad for two reasons. Your thermocouple goes from a $15 part that you can easily get many places, including locally, to a special part that costs $130.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.