Water heater thermostat replacement & leak repair

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Posted by: from Toronto
1/11/2014 at 4:05:49 AM

I need to replace the upper thermostat for a Giant brand Model 172E water heater. There are two identical water heaters in series, and they are about 10 years old. From what I've learned, it's a 2 heater non-simultaneous unit. The readings I'm getting from the terminals of the broken thermostat are very different from those on the working twin unit. Although very familiar with electrical work and electronics, I can't figure out how those readings are even possible if the thermostats are identical!

I cannot find a supplier for the same brand and model of thermostat as recommended on the heater manual. The broken thermostat looks 98% (not quite exactly) like the attached picture. It says Therm-o-Disc Type 7135 near the dial.

The single model sold by the big box stores (Home Depot etc) look very different, so I'm not sure I can use it. How do I go about finding out if they are compatible? Better yet if someone can recommend a couple of open-to-the-public plumbing/heating suppliers with more selection in North York/Toronto in case I need other parts.

Aside from the thermostat, there's also a water leak coming from in between the two heaters. About as much as a sink faucet turned on with a low but steady stream. The water is warm, which suggests it's from the working 2nd water heater. It's flowing from underneath the heater, not the supply pipe. And the fiberglass insulation in the bottom hatch of both heaters is very damp, especially in the working heater.

Is there anything I should check to possibly fix the leak myself before resorting to a professional? I haven't pulled back the insulation to reveal the heating elements, but if there's a leak there is it always a easy matter of replacing the element? Could it be anything else that doesn't involve replacing the entire unit?

These are a lot of questions, so thank you for any help. The friend I'm helping with these issues can't afford any more repair expenses after all the disasters that struck his home this year.

water heater thermostat replacement & leak repair
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Date/Time1/11/2014 at 9:03:09 PM

Replace the water heater. You have a faulty thermostat, a leak and it's 10 years old. It makes no sense to spend money to try and repair it (if at all possible). A new electric heater is around $350 plus installation.

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Jason in Toronto
Date/Time1/12/2014 at 1:38:10 AM

It's two heaters, so to replace both that's $1000 with installation he simply doesn't have after losing over $35k to the July flood in Toronto and urgent repairs. Thank you for your suggestion. I understand it's the easiest solution and if times were better not the most expensive of things, but he has already suffered the most expensive things and replacing the whole system must be a last resort.

There's one heater that might just need a $30 thermostat, and one of them might just need a new element. I don't want to discard that possibility just because it takes a little bit of investigation. Worst case I figure, if it's a tank leak, he could still have one working unit for a year or two with a minor repair or a transplant of parts. His family should learn to economize hot water anyway, in my opinion, both from an environmental perspective and to recover money from energy bills to offset recent expenses.

I'll let him know I haven't learned what to do about repairing it yet and it might come to replacing the heater as you suggested, but I hope someone will still answer the questions I asked in the OP. Fixing it and knowing he has to replace it very soon is much better than having to replace it right now without the cash.


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Date/Time1/12/2014 at 9:25:46 AM

Hi Jason.

I found the water heater model # on line and it shows as a 60 gallon unit. Why can't you take the worst one out of the loop and use it for parts to fix the second one. If it is a single family, should be no problem.

Google "model # 172e water heater" and go to the Giant Factories web page. Yours is a "Super Cascade"

This may keep them going until they can do the right repair which is the replacement as James recommended.

Good Luck with it!

Jim Kuzma

Kettleby Handyman Services

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