EXACTLY. Mine does this; after long motoring runs, I get warm water out of the cold side spigots.
Boat Plumbing - Potable Water - Backflow Preventer Before Heater?
- Thread starter jviss
- Start date
I see, mine has only one pump which outlet split to two route. One to cold water tap and another to hot tap via heater tank.
Pretty sure that a check valve will not protect you from engine antifreeze. Hot water flows out of the tank to the faucet. The check valve will not stop that so if engine anti gets into the potable water in the HW tank it will not be stopped by the check valve.
Also the only way hot water would "leak" back into the cold water side is through the cold water supply and that is a) closed, and b) pressurized by the pump.
all you are really going to accomplish is to add some pressure loss on the hot side of the water system and reduce the max flow rate. just another thing to break. KISS
Also the only way hot water would "leak" back into the cold water side is through the cold water supply and that is a) closed, and b) pressurized by the pump.
all you are really going to accomplish is to add some pressure loss on the hot side of the water system and reduce the max flow rate. just another thing to break. KISS
A couple of things, Bill. First, the check valve should protect the water supply. True, the hot side will be trash, but once it's discovered, the heater can be bypassed, and the check valve will have protected the water supply. True?
Second, I don't know what you mean by the cold water supply being "closed." Can you please elaborate?
Thanks,
jv
Second, I don't know what you mean by the cold water supply being "closed." Can you please elaborate?
Thanks,
jv
Not really. The flow rate is very high for this particular check valve: 34 GPM at 10 psi (my system runs 20 to 40 psi); , and the cracking pressure is 0.33 psi. One would be hard-pressed to detect this in-line, even with good measuring equipment.
Yes. Mine is the same. That's what I meant by both sides simultaneously.
If heat-pressurized water is in the heater, it can backflow through the heater feed line into your cold side, if there is no or a faulty check valve.
This is especially true if the pump is switched off and the feed is pressurized by the heater and not the pump and/or accumulator. But it can still happen when the feed is pressurized, depending on the pump's cutoff switch rating and the heater temp/psi. IE: if your domestic water pump cuts off at 15 psi, and you've got 180 degree water in the heater at 25 psi, the hot water is going to shoot out the cold side if faucet is opened and there is no check valve. The pump is not going to kick on until the pressure is back down below 15 psi. By then it's too late, the hot is already on its way to the cold outlet, pushed out more by the pump coming on at 15 psi.
We're only talking about a Coke can worth of hot water leaving the heater, but it's enough to badly scald an unsuspecting person.
Check out the schematic in that link early in the thread.
SO, who has this ever actually happened to? I've never heard of this concern, never the less to hear of it happening. Much ado about nothing, methinks. My head sink is maybe 5 to 6 feet from the water heater- never a problem.
[QUOTE="Ron20324, post: 1414912, member: 59774"
SO, who has this ever actually happened to? I've never heard of this concern, never the less to hear of it happening. Much ado about nothing, methinks. My head sink is maybe 5 to 6 feet from the water heater- never a problem.
[/QUOTE]
Not many... Because we all have check valves.
Although it happened to me and "Gettinthere" (read). Mine was stuck check valve.
That's 2 in a thread of 10 people.
SO, who has this ever actually happened to? I've never heard of this concern, never the less to hear of it happening. Much ado about nothing, methinks. My head sink is maybe 5 to 6 feet from the water heater- never a problem.
[/QUOTE]
Not many... Because we all have check valves.
Although it happened to me and "Gettinthere" (read). Mine was stuck check valve.
That's 2 in a thread of 10 people.
Jviss,
I just installed a water heater By-Pass kit Saturday. It came with a check valve and there was one already there from the factory. I replaced it with the new one but was wondering why it was there to begin with. My first season with this boat and it's a bit more complicated than my Cat 30. Thanks for bringing it up, it's good to get opinions.
https://www.wholesalemarine.com/cam...MI36X-_rGq1wIVqbvtCh3LtwK4EAYYASABEgIgdfD_BwE
I just installed a water heater By-Pass kit Saturday. It came with a check valve and there was one already there from the factory. I replaced it with the new one but was wondering why it was there to begin with. My first season with this boat and it's a bit more complicated than my Cat 30. Thanks for bringing it up, it's good to get opinions.
https://www.wholesalemarine.com/cam...MI36X-_rGq1wIVqbvtCh3LtwK4EAYYASABEgIgdfD_BwE
Hi Bob, My installation had a bypass, but it was a mix of components and kinda Rube Goldberg. Mine didn't have a check valve. I accidentally broke one white, plastic fitting as I was winterizing, probably just as well. I looked at the bypass kit you purchased, but opted instead for another Camco product, this one:
https://www.amazon.com/gp/product/B000BQUJL8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
This has two identical brass bypass valves, no check valve. One thing that bothers me is that I think there's a mismatch between the hose threads the the bypass valve threads. The valve is pretty clearly NPT on all ports, but the hose seems to bind as it is tightened, and I think it might be a straight thread. Is there a plumber in the house?
My view is that a check valve is a good idea, for a bunch of reasons.
https://www.amazon.com/gp/product/B000BQUJL8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
This has two identical brass bypass valves, no check valve. One thing that bothers me is that I think there's a mismatch between the hose threads the the bypass valve threads. The valve is pretty clearly NPT on all ports, but the hose seems to bind as it is tightened, and I think it might be a straight thread. Is there a plumber in the house?
My view is that a check valve is a good idea, for a bunch of reasons.
Except that there's already a backflow preventer at the pump.
How else would it maintain pressure...
Mine has the preventer in the output connector.
If you're worried about bacteria (or coolant re: another poster) back flowing in hot water on the feed side, then you should be worried about back flowing hot water on the feed side.
Although, all of these thoughts are valid. I'll have to agree with another that there are several good reasons for a check valve. It doesn't matter which is the best reason.
We could always ask @Peggie Hall HeadMistress
The hot water heater is downstream of the pump, agreed? So are all the cold water lines to the faucets. Bacteria will travel through the lines and come out the cold water faucets. You'll think you were drinking water in Mexico a few hours later. But hey not following manufacturers installation instructions is always a choice you can make.
Y'all are debating the need to ALWAYS install a check valve without knowing whether one may already be included, or even needed, in a particular mfr's water heater design. So I'd always follow the installation instructions for that particular water heater...if they call for one, install one. If they don't, I wouldn't worry about it.
Dave, except for any who've taken on water in a third world country or a contaminated well here, how many people have you ever met whose onboard fresh water has made them sick?
Dave, except for any who've taken on water in a third world country or a contaminated well here, how many people have you ever met whose onboard fresh water has made them sick?
Many people get sick and never know the cause. I'd hypothesize that many boaters don't drink their onboard supply using it for washing and cleaning while drinking bottled water. I agree follow the installation instructions.
Also key here is whether the water has chemicals added to kill bacteria. If we eliminate all possible sources of bad water and only fill with treated municipal supplies then that subset of boaters is likely less probable of getting sick.
Also key here is whether the water has chemicals added to kill bacteria. If we eliminate all possible sources of bad water and only fill with treated municipal supplies then that subset of boaters is likely less probable of getting sick.