CHECK VALVE help....

Hello everyone..
I've got an issue thats been nagging me for years, and I'm hoping that with all the great people on here, I can finally get to the root of the probem...

The issue is this: At times, when I turn on my domestic COLD water faucets any where in the house, I am greeted with about a 10-20 second suppy of warm, then hot water first, before finally getting the cold water I was expecting...the situation is worse in the Summer time, or when there is a particularly hot supply of water in my 40 gal. in-direct fired hot water tank.

To solve the problem, I installed a Check Valve on the cold water supply line, as shown in the picture I have provided. This has NOT helped, and the problem continues to this day! I can place my hand on the pipe on either side of the Check Valve and the pipe feels warm...this situation has most likey costed me hundereds of $$ in oil costs over the years as the slight draw down in the tank causes the boiler to come on...and in the Summer I have an outdoor sprinkler system that puts out thousands of gallons of water a day....

The water tank is only a couple of years old, (my second), and the problem existed before that...I keep the setting on it as low as possible since the problem seems to be worse when the water is hotter...PLEASE HELP!!

Thanks in advance!
DON

Is their a mixing valve on the outlet from the hot water heater that could be causing the problem ? Did you trace all your pipes that somewhere down the line a hot was T'd into the cold side ?

Try this, hold the pipe that you say is hot on the cold supply side before the check valve at the tank heater, have someone open the cold tap and see if the pipe gets hotter.

Fireman...You may be on to something that I have long suspected...

When I built this house, I installed a shower stall in a first floor bath as an after thought...(3 full baths)...as it turns out, this shower stall has been used a total of 2 times in 15 years.....anyway, I bought the hot and cold water faucets, drilled holes in the fiberglass shower, and installed each (hot/cold) to the appropriate supply lines...well..when the plumbing inspector came by, he say: Nope! thats a potential scalding hazard! gotta have a mixing valve!...but I already had the shower stall drilled and installed!..so..what I did to appease the man, was I purchase a (Sparco?) mixing valve and installed it under the floor of the shower so that the water would never get too hot, even if somone were to enter the shower and just turn on the hot water...so this valve has the hot and cold water feeding into it first, BEFORE feeding the shower head...this made the plumbing inspector happy, and he signed off..
This installation is, off course, down stream of the Check Valve, and even tho I always suspected that this could be the problem, I still could not understand the mechanics behind it...
Since the shower is never used, as a test I have been prepared to severe the darn supply lines to the unit completely to see if it helped...but I have been reluctant to do that just on my own hunch...
I can take a photo of the valve if it helps..
What do you think?

Thanks so much!
DON

I don not see a backflow preventor, only a check valve in the photo. Check valves may or may not stop gravity heat flow in piping.

What you may need is a heat trap. A heat trap is a inline device or a loop of pipe that will stop gravity heat migration. Search the internet for more information.

Another problem is if the cold water piping touches or is in the same insulation envelope as a hot water line. The hot water will heat the cold water. I have seen this happen in soffits where plumbing lines were run together with heating lines.

Thanks SteamUp...You know what?? You are right! It IS a check valve... ! Its been a while since the valve was installed, and in my research and reading since then, I have since mistaken a BFP with a check valve...

OK...so what would a check valve be used for??

WOULD a back flow preventer work in my situation?

Is a heat trap a type of valve that can be bought?

...fyi..my hot/cold supply lines are not close together..

Thanks!

While a check valve does prevent reverse flow, it is not a true backflow preventor by most code definitions. The valve you have has a flapper in it that hangs off of a hinge. The true seal occurs when there is a pressure differential across the flapper. If pressure is higher on the upstream side, the valve swings open with the flow. If pressure is higher on the downstream side, the pressure jambs the flapper against the seat creating a seal. If pressure is equal on both sides, the flapper just hangs there and may not seal tightly depending on how level the line is, thus allowing some minor gravity circulation.

Research heat traps on the internet. They are available through plumbing supply houses and are a inline device that discourages gravity flow. Many newer water heaters have them built in.

I noted that you said that you could go anywhere in the house and the situation is the same. You turn on the cold, it gets warm, then hot, then you get the cold correct? This occurs no matter what faucet you go to in the house. You have a cross connection where the hot is mixing with the cold somewhere. It starts out warm then the hot gets there followed by the cold which over comes the slight hot water infiltration.

The first suspect would be that mixing valve on that unused shower. Start with it and shut off the water supply for both hot and cold to it BEFORE that mixing valve. Let it sit, try it again. OR

manually trace the hot water line and find the cross connection.

A heat trap is simply a few elbows soldered up to make the water go down before it continues up. Heat rises, if asked to go down 6 or 8 inches it will not go by gravity.

A ball check has a spring loaded ball that closes and makes a one way valve. A swing check has no spring. Your pictured valve looks like a swing check. Water moving by gravity will go through a swing check but not a ball check.

You need to figure out where the water is moving and add check valves and/or heat traps to cure the problem.

At one point in time I DID feel the cold water and hot water supply lines leading to that Sparko valve I mentioned above, and EACH was warm, even though the shower never gets tuned on...I can post some pics of that set up if it helps...

Thanks so far for all the input!

Maybe a Expansion tank is needed?

http://www.watts.com/pages/learnAbout/t ... eneralinfo

Also, there are taps that TEE the lines together to circulate the hot water thru the cold, so you don't have let the hot water run forever. Make sure you don't have one of these.

http://www.watts.com/pages/_products_de ... p?pid=6678

Don,

Ditto Freddy. I had the same issues. I put in a new tank when I installed my Kaa-2, and I did what he illustrated. I Ran both in and out piping down 12" or so. Here's a pic, but not a very good one;

Ignore the piping on the right side of tee. It's from the pre-heaters on boiler piping above [used when boiler runs only]. Also ignore the 3/4 run 1/2" branch tee. It is fill water to the boiler.

The pipes in and out of the tank are against the wall. They simply run down, then back up, then to/from tank. It was hard for me to do it, as it looks dumb as heck, but it works. I thought "this will never work, and I'll change it later". The "riser" pipes are cool when the water is parked.

I also didn't like the little rubber "check valve" gizmos in the tank inlet/outlet that are there to prevent heat loss. I pitched them.

Dave

p.s. - yes, I did finish the piping from the "pop-off" valve

If the mixing valve is the problem and you have to replace/rebuild it, why don't you take it from the shower where it doesn't see any use and place in at the water heater to protect your whole house (or the occupants living in it).

stoker_RI wrote:At one point in time I DID feel the cold water and hot water supply lines leading to that Sparko valve I mentioned above, and EACH was warm, even though the shower never gets tuned on...I can post some pics of that set up if it helps...

Thanks so far for all the input!

I forgot that this is a common issue also. There should be checkstops in the shower mixing valve. They should be standard but sometimes they are not. Checkstops are minature check valves like a ball check.

WNY wrote:Maybe a Expansion tank is needed?

http://www.watts.com/pages/learnAbout/t ... eneralinfo

Also, there are taps that TEE the lines together to circulate the hot water thru the cold, so you don't have let the hot water run forever. Make sure you don't have one of these.

http://www.watts.com/pages/_products_de ... p?pid=6678

Lack of an expansion tank would not explain the migration of heat flow unless there was a leaking valve such as at the mixing valve. Overpressurization is a concern with the check valve at the water heater. If the check valve truly closes and all of the faucets are closed and the water heater kicks on, the expanding water would have no place to go and overpressurize the water heater. You would see the relief valve letting go if that was the case. If it is not overpressurizing, that would support the theory that the check valve is not holding or the shower mixng valve is leaking by to the cold water. But since the problem is in the whole house, not just the shower, I would bet the check valve is not holding. Is it warm on the cold water side if the check valve?