I assume your $1000 figure includes a new water heater since you can buy a thermal expansion tank for less than $50 and a new pressure regulator valve for much less than that.

Tom

Um...no. That did not include the HWH itself being replaced.

Are you talking about something to heat just your water or something to heat your house? I've seen many gas hot water tanks and I've never seen one with an expansion tank. Go into Home Depot and price a gas hot water tank...probably less than $400. Ask if it needs an expansion tank. Maybe it't some regional thing, but I've never heard of it.

You can add a small expansion tank to an electric hot water heater. Is that the heater you are talking about? If so, the pressure valve should cost around $25.00, and as mentioned above, perhaps $40.00 to $50.00 for the expansion tank, plus 30 minutes to one hour for labor.

Well actually I don't even care about adding the expansion tank - I had just been told that to do any work on this system they needed to add it for code. The water heater is gas and only heats water, not the whole house.

I can't belive that if the pressure valve is bad (which is still not determined) that to replace that would be almost $1k. Really, I just have a small trickle coming from the overflow. I just think that I'm a good target for plumbers.

Call someone else and get a quote on a new hot water tank. I bet it will be less than $1000.
Has anyone else heard of the requirement of an expansion tank on a gas HW heater?? I live in an area that is mostly piped in natural gas. The supplier is the fussiest that I have ever seen in following national codes. I have several gas HW tanks in apt. buildings, and as a precaution, have them inspected once per year along with the boilers. I just had them inspected a few months ago. I have never heard of an expansion tank on a heater. If this is residential, I can almost guarantee that if the code required it, I would be forced to put them in.

There are two things that could be meant here by 'pressure valve'.

The 'overflow' is from the temperature & pressure relief valve. These commonly get gunked up with sediment after a while; if you have a plumber replace it, it shouldn't cost much more than the trip charge.

If you have a pressure reducing valve or backflow preventer - most homes don't, but some do - then you DO need a thermal expansion tank. If this is the case, then your pressure relief valve was doing its job by keeping your water heater from possibly bursting.

My guess is that this is just your temperature&pressure relief valve wearing out. You should get it fixed, so it will function properly if you DO have a problem - this valve is an important safety feature. But it shouldn't cost much to get it fixed.. will probably take the plumber maybe 15 minutes and a $10 part. (Which of course will cost you more than that.. but not $900 more!)

Here is a link that might be useful: More info on TPR valves

Perel, you are correct in saying that we are talking about several things here. We DO have a pressure reducing valve (this is what our plumber was calling the 'pressure valve.' So we are talking about replacing that valve, along with the overflow valve (what you are calling temp & press relief valve) and also installing the thermal expansion tank.

The thing that is really troublling is that he didn't examine any of these just looked at the system and said, replace the two parts and add the tank. That will be $1000.

This system has been operational for 17 years, so it's likely something does need to be replaced, but the cost seems incredibly high for these three parts + labor.

Thank you for all the information everybody. I guess what I should do it get another plumber out here to evaluate - of course that costs money too! It's crazy. I think I need to go to plumbing school.

Perel,
Is this something new on expansion tank when a house has a check valve or pressure reducing valve? I've had a bunch of tanks installed and instpected over the years and no one has ever asked or looked for check or reducing valve or mentioned expansion tank. I would think that in case things heated up too much in the tank that the pressure relief valve would just blow off. Why the expansion tank? Is this part of the plumbing code or gas code?

Approx. 4 years ago the city put new water lines in and installed reducer valves and expansion tanks in all the houses on our street. The water tower is at the end of our street [1/2 mile dead-end street] and I presume the pressure was too great this close to the tower.

The TPR valve is a safety device. It is not intended to blow off on a regular basis. Doing so shortens the life of the valve, and also indicates that the water pressure is getting WAY over where it should be. That's bad for the washers in all your faucets, possibly causing a dripping faucet.. and worse, it's bad for the fill valves and supply hoses in your washing machine and dishwasher - increasing your risk of a catastrophic fill valve or supply hose failure.

And yes, installing an expansion tank when there is a backflow preventer (check and reducing valves are backflow preventers) is a code requirement now in many areas. Even if your system is grandfathered, if you have a backflow preventer, you should have an expansion tank.

Hopefully lazypup will come along soon and give one of his great explanations..

Rather than wonder, a quick Google and wadda ya know... "thermal expansion"

click here for info on thermal expansion

All very interesting, but my question is really about how much this should all cost. Anybody out there have a ballpark?

airren,

"All very interesting, but my question is really about how much this should all cost. Anybody out there have a ballpark?"

Cost will vary by location. Once you understand exactly what you need, call at least three plumbers and have them come out and give you a quote. If they quote over the phone they can't give an exact price and will be quoting based on YOUR description so an on-site inspection is a must.

Then you'll have an idea of what the local plumbers are charging.

Don't dally, if you have a closed plumbing system (and with a PRV you do) then your WH and plumbing is being exposed to higher than normal water pressure. The sooner this is corrected the better. All that is presently seperating you from a plumbing disaster is the $10 T&P valve, and that valve is supposed to be the last resort.

I suppose you are right, unfortunately the plumbers in my area charge $150 just to come out to your house even for an estimate. If I go with one of them, obviously the $150 will be applied to the work.

You are at the mercy of your local plumbers, as we all are.

Do ALL the plumbers in your area charge for estimates?

You need to have this repair done and done according to code.

Ask your neighbors if they've had any plumbing done. They may recommend a plumber or they may tell you who to avoid.

The plumbers that I have called so far do. I think I'm just going to take your advice and use the plumber that my neighbor recommends. At least that way I have less of a chance that they will overcharge knowing that they could possibly lose the business of two customers.

Thanks for everyone's help on this.

I can tell you that I appreciate the information on expansion tanks. I had never heard about that requirement, but maybe because I don't have any check valves.
So, is the theory that without a check valve, the expanded water is forced back into the supply from the street? Therefore, no expansion tank is needed?

coolvt,

"So, is the theory that without a check valve, the expanded water is forced back into the supply from the street? Therefore, no expansion tank is needed?"

That is correct BUT somewhere in the 90's the law (code) was changed to prevent the backflow of potable water from a house back into the water system eliminating the possibility of contaminating the water system by backflow from a house.

I believe that all new contruction from that point mandated a check valve. The check valve can be unique or incorporated into a PRV (pressure reducing valve) or in a water meter. You may not even know that you have a check valve making your house a closed plumbing system.

To be safe, buy a Watts IWTG at Home depot. It's a pressure gauge with a red tattletale needle that sticks at the highest pressure. You can screw it right on to a hose bib or the drain valve on your water heater. If you use the drain valve on your WH there's a chance the valve may leak when you're done if you haven't been routinely draining your WH. If there's a pressure spike due to thermal expansion you'll see the needle up at 120lbs or higher.

Watts IWTG gauge here

If you see those high pressures then you'd better get on the horn with a plumber or fire up the torch.

Where I live they added check valves as meters and PRVs were replaced. Code for new construction here now mandates two unique forms (methods) of thermal expansion control usually resulting in the installation of an expansion tanks and something like a Watts GOV-80 toilet ballcock or a Watts BRV (combination ball and pressure relief valves).