Hot Water Heater -It is all about up-charges

Mike Henderson said:

I don't understand why thermal expansion would require an expansion tank. The water system in your home is open to the supply - at least it is in a municipal system. If the water expands, it will just flow back into the pipes supplying the house. This is true even for a water heater. The water heater is "open" in that water can flow backwards through it as well as forwards.

So there should be no need (that I can see) for an expansion tank in a home supplied by a standard municipal water system to accomodate thermal expansion.

Water hammer is a different situation and it may (or may not, as Travis points out) help out.

Mike

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It all depends on check valves Mike. My system, which is a boiler and does not have a hot water heater...it has a hot water storage tank instead. Big difference!

My boiler is a closed circuit heating system. The only reason it is tied in with my water system at all, is to make sure the water inside the internal boiler loop,does not evaporate the water away during operation. It is tied into my water system via ½" line that injects the water into the boiler as needed. This passes through a check valve that isolates the boiler water from my domestic hot water.

On the storage tank end, my boiler water never comes in contact with my domestic hot water. It circulates through a coil which in turn transfers that heat to water in the tank. For safety reasons, any loss of pressure in the internal boiler circuit, shuts off the boiler. That is to prevent nasty internal boiler loop water from getting into potable domestic water.

Now in a water heater you are indeed right, thermal expansion of water, upon being heated, could flow back into the pipes and expand harmlessly...as long as the plumbing system is long enough that is. If the water heater is plumbed to heat say just one facet not far from the heater, then problems could result, especially when using plastic pipe. There would not be enough room for the expansion to take place.

Another area that is often overlooked, but also against code (at least here in Maine) is in using a water heater as a heat source for radiant floor heating. In that case you are using the water heater as a domestic heat living source and while not permitted, is often done. Not using a thermal expansion tank in this case could prove to be catastrophic because of the changing thermal dynamics that the system is constantly undergoing.

Keep in mind too Mike that the principal role of a thermal expansion tank is to control variances in pressure, not just thermal differences that create differences in pressure. There are other instances that cause pressure spikes.

After installing my system I was amazed at how often the expansion tank does its job. Just about every time the boiler comes on (modulates) the expansion tank comes into play. I am sure this happens more on my system because my boiler drops to 80º before rising back up to 180º, but a hot water heater cycles as well, just not so often or to such temp extremes. Still I can see why some municipalities require them now. For 60 bucks, its cheap insurance.

There was an episode of Ask This Old House where Richard installed a thermal expansion tank for the homeowner. The pressure relief valve on the water heater was opening just like Jim described. Those of us with wells don't need them because our bladder storage tanks allow for the expansion.

Most of the municipal water systems use both massive pumps and the water towers to regulate pressure. Since many smaller systems might only have one tower, the pumps have to be capable of maintaining pressure when the tower is out of service. There are usually booster pump stations located around the system too. On modern systems, all of the equipment is tied together by wired and wireless communication to a central control system to coordinate everything.

The expansion tank thing is a new one on me. Sounds like some bureaucrat designed regulation.
We had a new GE water heater go out. Problem, yes but it was under full warranty. Now, hear this GE and 'warranty' used in the same sentence is an oxymoron. Long story short: dealer referred me to GE. GE supposedly doesn't even have a department to handle these issues. Gave up fighting. Of course, gave up on ever having anything in my home with the GE name on it.
Ended up calling electric company and got a Marathon heater put in. Supposedly the best heater in the world. Pay $11.00 a month lease. No installation charges. They maintain forever. I feel it is worth the price.

That makes a lot of sense, Jim. I think the water company here does the same thing. It's a lot easier to provide high pressure and regulate it at the home than to try to maintain appropriate pressure throughout the whole system. And the regulator would act like an anti-backflow valve - so some expansion technique is needed.

Regarding disposing of the old heater, the waste company who serves my area will do two "special" pickups per home, per year. So I just called them, made an appointment, and put the old heater out on the street on that day. They came by, picked it up, no problem.

Mike

Mike Henderson said:

That makes a lot of sense, Jim. I think the water company here does the same thing. It's a lot easier to provide high pressure and regulate it at the home than to try to maintain appropriate pressure throughout the whole system. And the regulator would act like an anti-backflow valve - so some expansion technique is needed...Mike

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Mike,
That's how it's done. My sister & BIL live across town, and at a higher elevation than me, and their water pressure at the tap is about 35psi. Their flow rate is also terrible - by my standards. It takes about ten minutes to fill the sink for dish washing and at least three minutes just to refill the toilet after a flush. With no regulator on their service, they don't have any need for an expansion tank, though.

BTW, the expansion tanks are super simple to install. It can be pretty much anywher in the incoming cold water line, and only requires a 'Tee' fitting with ¾" pipe (female) threads. The device comes with a male threaded finning on it, and just screws on. Replacing mine, after turning off the water supply, took less than five minutes.

Your installation, from the picture, with its short extra length of pipe, probably took your plumber all of ten minutes to do.

Back to the original thought of the thread......

It always singes me when they pull this stuff...........I have very little patience for this type of stuff....


I always tell these companies or the car saleman.........I want to know the bottom line.....I don't want any surprises.....I want one price...or I go elsewhere......Most of the time I get what I want......Sometimes I have to walk....

Ken Fitzgerald said:

Back to the original thought of the thread......

It always singes me when they pull this stuff...........I have very little patience for this type of stuff....


I always tell these companies or the car saleman.........I want to know the bottom line.....I don't want any surprises.....I want one price...or I go elsewhere......Most of the time I get what I want......Sometimes I have to walk....

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I know there are lots of crooks out there, but to be fair, the worker doesn't know what s/he's going to get into until they see the actual installation. Even when I do the work myself, I sometimes find problems that I didn't expect after I get into the situation.

Mike

The thing that was sprung on us in 2002 was the requirement of a chimney inspection when you replace a gas or oil fired appliance vented into a chimney. An inspection certificate was required before the permit for the appliance could be closed.

Inspector #1 (who installs chimney liners BTW) said that the clay tile chimney liner had cracks and missing grout. His estimate was $xxx dollars (don't recall amount but it was in the 2-3 X contractor saw range). The plumber on the job who was replacing the water heater (and referred Inspector #1) shrugs and said - yeah, he seems to condemn a lot of chimneys.

We found Inspector #2 who came and gave the chimney a clean bill of health.

It's an untapped market I guess. I'd prefer to have inspectors that have no financial stake in the game.

We've had more issues with shady plumber in general. We were finishing the basement, so before hand we had a plumber come in and replace the house Pressure Reducing Valve and all the spigots. 1 year later the PRV fails - we have 135 PSI water pressure in the house!

We call the plumber who's crew installed the failed PRV. After some discussion (they couldn't believe the PRV failed) they sent someone out. He walks in with a new PRV in hand, looks at our installed PRV and says "Where did that %#@% PRV come from? That's not what we installed! ". We say it is. They say it's not. We come to the agreement that they wil install the NEW PRV and they are going to do some research on what happened.

A few days later they call back and say - never mind, we'll take care of it. Apparently they had an issue with one of their plumbers. They sent him out with a GOOD QUALITY PRV and he installed a CHEAP JUNKY PRV and kept the good one. He probably installed it himself on the side or sold it. Your at the mercy of the tradesman - I wouldn't know a good PRV from a cheap one.

Caveat emptor

Jim

Mike Henderson said:

I know there are lots of crooks out there, but to be fair, the worker doesn't know what s/he's going to get into until they see the actual installation. Even when I do the work myself, I sometimes find problems that I didn't expect after I get into the situation.

Mike

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Mike...I agree but generally they can give you a worse case scenario ....even while on the phone.