Is the in-line check valve needed for for the hot water line

[RonE]

Good morning....
Another little problem developed over the weekend, and once again I believe it has been a
problem gone undetected for sometime.
The water pressure pump was going continously sunday afternoon, I found out two things yesterday,
one is that there was a crack in the in-line check valve, that is in the run between the water heater
and the fawcet. And two, once I removed it and connected the hose directly, the pressure pump never
went on!!!! This was something I thought was normal, cause once the switch for the pressure was on,
it would go on every 5 mins or so, every since I had the boat, I would tell the wife only to turn the pressure on when she needed the sink... crazy. Yesterday, once I removed the leak, the pump never activated until I opened the fawcet. To make matters worse, the huge rust on the water heater is probably due to the leaking check value...
Ron   

[Footloose]

Ron

Not sure why you would need a check valve in the hot water line.  When in doubt, take it out.  The water pump should only run when you open the faucet.  If it is running between openings, you have a leak.

[Kevin Henderson]

Ron

Not sure why you would need a check valve in the hot water line.  When in doubt, take it out.  The water pump should only run when you open the faucet.  If it is running between openings, you have a leak.

Just curious on this one.  My water pump will also come on for only a short instance about every 5-10 minutes when I am not using the faucet.  Is this definitice that there is a leak?  My assumption has been that there would naturally be a bit of air (pressure) loss somewhere within all of the connections and faucet.

[Les Luzar]

Kevin,
My water pump acts the same as yours. When I leave it activated, the pump will come on every now and then. I never timed it, but I too thought that this was normal.....

[Footloose]

We leave our water pressure pump turned on when cruising and it will go all night without running.  If it is running,without openingthe faucet, you are losing pressure somewhere.  The decrease in pressure is what trips the switch to pressurize the system.

[Ralph Masters]

Your water pump should not cycle on unless you open a faucet.  If it is cycling on and off you have a leak in the system some place or your pump is losing pressure backward to the tank via the internal backflow preventer. 
When we return to the boat on Saturday after leaving every thing turned off for the week we still have pressure in the faucet.  A good check of your systems integrity.

Ralph
Ciao Bella

[Fred Koehlmann]

Ron E: The inline check value is on the cold water supply line to the hot water tank on our boat. This ensures that the water flows in one direction, especially when you have both hot and cold values open (and at different amounts). Since the unit is plastic (at least on our boat) I would keep it on the cold water supply side.

As for the occasional starting up of the pressure pump, both Kevin and Footloose are right. The pump comes on occasionally when the line pressure has dropped to a certain point. In an ideal set up (and it sounds like Footloose has one) the pump comes on only when you open the faucet. But almost everyone seems to have a bit of a pressure loss. I know we have a less than perfect faucet in the head, and that my hot water tank install this spring has a slight drip at one connection (not enough to make it to the bilge cause it dries up before it gets there), but all in total it makes the pump come on about every 20 - 30 minutes. At night we just turn it off.

I'll be looking at replacing the head faucet this winter, and maybe I'll tighten that drip as well.

[Roger Blake]

My pump would come on at 5-10 minute intervals too...until all of a sudden it just came on and stayed on (started draining my water tank to the bilge). I have a round filter under the sink (well, under the self under the sink), which clogged and then separated. Removed, cleaned, and reassembled it, problem gone.

[Roc]

Here's what I think as why my pump cycles every so often.  At the start of the season, I don't notice this happening.  As the season progresses, that one second cycle starts happening. I came to this conclusion because every so often, I need to flush out the airator screen on the faucet because calcium deposits build up, restricting the water flow.  Apparently, the water in the town where my marina is might be a little hard.  I figured if this build up happens at the faucet, it might also happen inside the diaphram in the pump, causing it to not seat perfecly and thus leak, ever so slightly internally, between the pressure and non pressure side.  My guess is when I decommission the water system, the pink antifreeze might flush some deposits out of the pump.  Also, in the spring, I shock the system using bleach (Peggie Hall's method), which might also loosen the deposits in the pump.  So at the start of the season, the internal parts of the pump are probably very clean.  That might be why early in the season, I get no pump cycles, but over time, the build up happens and then the cycling starts.  Since I searched and searched for leaks, but never found them, this might be the culprit.

[Ron Hill]

Guys : If you hear the fresh water pump cycle 95% of the time it means you have a water leak - somewhere !?!.  It is possible to have some  crud bypass the filter and get into the pump diaphram.  Had that happen and is why I installed a finer mesch screen.

Frederick is correct on the one way valve to the water heater.  This past week I change mine after 24 years as it had blown the gasket that's inbetween the two halves. 

[Ron Hill]

Guys : On a MKI you can see the one way valve from the side door by the water heater.  It is a black square with a barbed 1/2" inlets on either end.

To change it out you'll probably have to remove the drawer and the frame under the sink.  That is "a bummer", but I don't think you can really get at it from the side door. 

[RonE]

Hey Ron I was waiting for you to chime in,
A couple of things, this one way valve was accessable via the side panel, but it was on a hose line coming from the water heater to the faucet. It was cracked and spewing right out. I removed it and connected the hose directly. The leaked siezed and the water pump stopped, now the only time it goes on is when you open the faucet. The way it suppose to operate.  My question is, do I need to replace the valve, and if I do where do I purchase one. I have not found it on line??
Thanks Again Ron

[Gary]

It is called a check valve and an amazon search for check valve will bring up a Shurflo http://www.amazon.com/SHURflo-340-001-In-Line-Check-Valve/dp/B000BGJWF2/ref=sr_1_7?ie=UTF8&qid=1347102393&sr=8-7&keywords=check+valve.

The check valve is to prevent back pressure and hot water access to the to the cold water feed. All the lines and especially the fresh water pump are going to receive extra water pressure and heat migration. You can tell that your check valve has failed when you turn on cold water and warm water comes out first, sometimes with a spurt. If you are motoring for extended periods the water in the tank does get very hot and builds up extra pressure to the whole fresh water system.

Do you absolutely need it? Probably. I have gone without a leaking check valve by bypassing the old valve when it failed. Got hot water at the cold water outlet and some extra pressure...I would relieve pressure when motoring by opening the cold water faucet occasionally. That kept everything under control until I could get a new check valve.

Gary

[mainesail]

It is called a check valve and an amazon search for check valve will bring up a Shurflo http://www.amazon.com/SHURflo-340-001-In-Line-Check-Valve/dp/B000BGJWF2/ref=sr_1_7?ie=UTF8&qid=1347102393&sr=8-7&keywords=check+valve.

The check valve is to prevent back pressure and hot water access to the to the cold water feed. All the lines and especially the fresh water pump are going to receive extra water pressure and heat migration. You can tell that your check valve has failed when you turn on cold water and warm water comes out first, sometimes with a spurt. If you are motoring for extended periods the water in the tank does get very hot and builds up extra pressure to the whole fresh water system.

Do you absolutely need it? Probably. I have gone without a leaking check valve by bypassing the old valve when it failed. Got hot water at the cold water outlet and some extra pressure...I would relieve pressure when motoring by opening the cold water faucet occasionally. That kept everything under control until I could get a new check valve.

Gary

In an ideal installation there should be a check valve. An ideal installation would also have an diaphragm accumulator tank to allow for smoother water flow, less pump cycling and the expansion of water in the system when heated. The hose in the system, ideally PEX, would also be temp rated to what the max potential of the water heater is and would not be cheap clear PVC. It would also have a thermostatic mixing valve on the water heater to prevent scalds & burns by water heaters heated off the engine. The ABYC is looking into requiring mixing vales. Sorry for the rant...

I would never install a water heater without at least a check valve or tempering valve but many do....

[Gary]

Mainesail...

Thanks for weighing in on the definitive need for a check valve in the hot water system. What you say is detailed and pursuasive. It was my intuitive sense that the check valve was important...you have made the case clear !

Thanks.

Gary