Water Heaters - Expansion Tank...opinions?

Hello -
I had my Fall maintenance done on my heat pump this morning and while the technician was looking at my heat pump, he also suggested I have an expansion tank installed on my water heater. He said his company could install one including the tank for $200 total. I've just now started to read up on them online and I've got to be honest...I've never had one on my water heater in the 10 years+ I've owned my home; I don't believe my parents have ever had one either in the 50+ years they've owned theirs. Actually, I don't know if I've ever heard of one mentioned (or even seen one) until today so it makes me a little hesitant that he's just trying to drum up more business for his company.

Does anyone have any insight or opinions on this? I've used this company for about 10 years now and this is the first they've mentioned it to me; granted it's a new technician. Is this a nescessity for a water heater? I just replaced the water heater last May so it's pretty new. Does installing an expansion tank have any benefits or drawbacks? Will it save me money in the long run? I'm open for all opinions. I'm just a little skeptic right now at his intentions. Thank you!

It sounds like a sales pitch to me. Are you sure that he was going to do it through the company or is it something he was going to do on the side?

I got that impression too. He was suggesting that he does it through his company instead of by himself. Even so, I agree with you...I think it was a sales pitch. Thank you!

An expansion tank is necessary if you have a sealed water system.

In the past, water systems usually weren't sealed. Water could come in from the street, and could also move out from the house towards the street when cold water in the water heater expanded in volume. No problem.

These days, many utilities are installing one way valves at the water meter when they do maintenance or repairs, which create a sealed system. Homeowners who install a pressure reducing valve also create a sealed system.

With a sealed system, water can come in from the street but it can't move out towards the street. When the water heater heats a large volume of cold water, the water expands in size physicall by about 2%. This will cause the water pressure to spike until the pressure reducing valve opens to bleed off the water causing excessive pressure.'


If you don't have that kind of problem, you don't need an expansion tank. Installing one when you dont need one is a waste of time and money.

Thanks for the helpful information! I really appreciate it! I'm on city water and in a fairly new home. I'll check into if I have that already installed on my meter. I have a feeling it's not a necessity for me. Thanks again!