Water Softener Install - Check valve need?

[Tort]

I am replacing old water softener with a new model, (waterboss Pro series 51PSB) and have a well water supply. The Waterboss install instructions recommend installing a "check valve" between softener and water heater if there is less than 10 feet (3m) of pipe between those two appliances. The home was built about 13 years ago using copper pipe and their is about 7 feet pipe (< 10 feet) between the old softener and water heater. There is NOT a check valve. Questions. (1) How critical is the "check valve" to operation? (Waterboss could not explain rationale). (2) If it is critical, is there any advantage of using spring valve or swing gate design for a well-based system?
thanks

 

[Reach4]

Speculation 1: The rational I came up with first is that if the water heater heats water, that water expands. If that expanded water flows through the softener, the meter can detect that flow, and think you have used a little more soft water than usual.

Another less common thing is if the WH has a thermal expansion tank, water pressure changes could cause flow in and out of the expansion tank. I think if you have a well, and an expansion tank at the WH, you would want the air precharge set to your maximum pressure. But normally with a well, you don't have a thermal expansion tank at the well. Yes, you would get that thermal expansion effect, but again it is a small amount.

If you would put in a check valve, it would be important to have a thermal expansion tank at the WH.

Speculation 2: My second idea is probably closer to what they are thinking. They are thinking of hot water expanding and passing thru the softener, and doing some damage due to the temperature. I have my doubts on that being a real concern, but I could be mistaken on that.

 

[Sponsor]

 

[Tort]

Speculation 1: The rational I came up with first is that if the water heater heats water, that water expands. If that expanded water flows through the softener, the meter can detect that flow, and think you have used a little more soft water than usual.

Another less common thing is if the WH has a thermal expansion tank, water pressure changes could cause flow in and out of the expansion tank. I think if you have a well, and an expansion tank at the WH, you would want the air precharge set to your maximum pressure. But normally with a well, you don't have a thermal expansion tank at the well. Yes, you would get that thermal expansion effect, but again it is a small amount.

If you would put in a check valve, it would be important to have a thermal expansion tank at the WH.

Speculation 2: My second idea is probably closer to what they are thinking. They are thinking of hot water expanding and passing thru the softener, and doing some damage due to the temperature. I have my doubts on that being a real concern, but I could be mistaken on that.

thank you!

 

[LLigetfa]

Speculation 2: My second idea is probably closer to what they are thinking. They are thinking of hot water expanding and passing thru the softener, and doing some damage due to the temperature. I have my doubts on that being a real concern, but I could be mistaken on that.

That is my read as well. There is another concern related to reverse flow if a hose bib is connected before the softener. When that hose is used, the water pressure drops and the higher pressure in the pipes upstream of the water heater reverses through the softener. How much reversal depends on how much piping there is and how elastic it is.

If a check valve is deployed, then you also need an expansion tank for the water heater.

 

[ditttohead]

The primary reason is for preventing hot water damage to the system. In my 30+ years I have seen countless warped riser tubes caused by hot water backing up into the system. I am sure I have pictures in my computer at work, maybe I will post some next week. This can also damage the tank, valve etc. A check valve is a good idea, but as stated by LLigetfa, you must install and maintain a properly sized thermal expansion tank or you can cause damage to the water heater. The check valve has the added benefit of reducing "ghost flow", water that is counted by the meter but is not actually used.

 

[Tort]

thanks for all the assistance. Are all check valves the same?

 

[ditttohead]

I used to be partial to spring check valves but after seeing so many fail over the years compared to swing checks I may be changing my mind. If I had my choice I would go with a ball check. In general, consider check valves a maintenance item. Replace them every 10 years and you should be good.

 

[Reach4]

thanks for all the assistance. Are all check valves the same?

How about adding 4 more feet of pipe to the path instead?

Also, in counting the pipe length, remember the vertical part of the path too.

 

[ditttohead]

LOL, just make your plumbing look like this.

While were at it, does this count as an air gap?

 

[Tort]

I did think about adding 4 more feet of pipe but would need to create "square shapes" of pipe and besides looking funny, thought that the increased amount of vertical rise might create some other flow dynamics. I like straight lines. Love the pic that of outdoor pipe layout that Dittohead added!!!

 

[Reach4]

I would not install a check valve, unless I felt the pipe near the softener, and found it warm at times. Let us know if you detect pipe warmth.

However I do like having a cartridge filter either before or after the softener. If you put one after the softener, I expect it would be more of an isolation than 4 more feet of pipe. So you get something useful.

With a cartridge filter, you have to be concerned that something goes wrong. I keep a spare o-ring in case the old one will not go back. The other way to handle the problem is to have a 3-valve bypass around the filter, or to have the filter have its own bypass.

 

[ditttohead]

Sorry to disagree with you Reach, but considering the low cost of a check valve and a thermal expansion tank, and after seeing way to many destroyed units over the years... I just got a filter in a few days ago that was ahead of the water heater, it literally looked like a frogs throat. If the homeowner ever runs an excessive amount of hot water and drops the temperature significantly, the water will expand as it is heated as much as 4%. Consider a 50 gallon tank, that's 2-3 extra gallons of water that needs to go somewhere. It will simply back up the pipe and into the softener. If I can remember I will post a picture of the filter housing, it is very impressive in that it did not fail or leak.

 

[Reach4]

Sorry to disagree with you Reach, but considering the low cost of a check valve and a thermal expansion tank, and after seeing way to many destroyed units over the years... I just got a filter in a few days ago that was ahead of the water heater, it literally looked like a frogs throat. If the homeowner ever runs an excessive amount of hot water and drops the temperature significantly, the water will expand as it is heated as much as 4%. Consider a 50 gallon tank, that's 2-3 extra gallons of water that needs to go somewhere. It will simply back up the pipe and into the softener. If I can remember I will post a picture of the filter housing, it is very impressive in that it did not fail or leak.

I was saying that I would not want to put a check valve after the softener. Are you saying that a check valve there should be routing.

Do you think a well system should have a cartridge filter? I have mine after the backwashing filter and before the softener.
Any hot water expansion will pass thru the softener, thru cartridges, thru the backwashing filter and into the 44 gallon pressure tank. No thermal expansion tank for the WH, accepting there will be a bit of phantom gallons. I probably have a good 10 ft of pipe out of my softener to the WH.

If I had city water, I would want a smaller cartridge filter or a wye filter. If there was a chance that there was a check valve at the meter, I would have a thermal expansion tank at the WH. When I did have city water, I had no filter and no softener.

So what is it that you disagree with? The idea that putting a cartridge filter after the softener would be as good as a piece of pipe to keep expanding hot water from bothering the softener, because a cartridge filter is probably as thermally fragile as a softener?

Consider a 50 gallon tank, that's 2-3 extra gallons of water that needs to go somewhere.

Heating 50 gallons of water from 40F to 140F gives 50.6 gallons. So only 0.6 extra gallons to go somewhere.

I used the calculator at https://www.engineeringtoolbox.com/volumetric-temperature-expansion-d_315.html with a 0.00012 coefficient, since I was working with degrees F.

 

[ditttohead]

Sorry, I am not understanding your question. No disrespect meant at all, just 30+ years of field/manufacturing experience. After seeing countless failures caused by thermal expansion, and considering the extremely low cost of a quality check valve/thermal expansion tank when a system is located close to a water heater, I tend to err on the side of installing a$10 check valve and a $45 thermal expansion tank rather than hoping that 95% of the time that no problem will occur... this still leave 5% of the time that a major problem may occur. I am not rich by any means, but <$100 is cheap insurance compared to spending hours if not days of labor clearing line of resin or other medias should a problem occur. A recent problem that occurred cost me over 150 hours of high cost labor due to a $5 error, needless to say, as a manufacturer I have a very different perspective. When someone sends you a bill for 100K, your mindset changes to "the little things matter". Especially when we are talking about <$100 of properly installed low cost/maintenance components could have eliminated the problem in the first place. Regardless, a thermal expansion tank is a cheap item that can prevent a lot of plumbing problems including ruptured hoses, flex lines etc. and not just at the filtration equipment, laundry, dishwasher etc. Thermal expansion is nothing new or exciting, it has been understood for decades at minimum. When water heats, it expand, that hot water has to go somewhere. It only has 1 direction to go, back to the city. If your water softener/filter is between the city and the water heater (which it is 99.99% of the time) that is where it will go. I design and sell units that are rated for up to 180F, but these are very specialized pieces of equipment utilizing stainless steel tanks and brass control valves with specialized rubber materials that can withstand these higher temperatures... Even lower temperature <150 degrees are still limited to specialized designs including vinyl ester tanks, brass valves etc. and take careful consideration in their design to ensure reasonable service intervals. If we were to use your numbers, assuming 3/4" type L, we can simply estimate that 10' would hold .25 gallons of water... and a simple plastic filter is probably far more fragile than a fiberglass wound mineral tank that is regularly tested by ASME to 600+ PSI. https://www.pentair.com/en/products/residential-water-treatment/professional-series/asme-tanks.html. When you install equipment near a water heater, install a check valve and thermal expansion tank to prevent problems. If you are on a pumped pressure supply system from your municipality (not a water tower) install a pressure regulator and maintain it. If you have stainless braided flex lines, replace them every 5 years. Some companies offer a 10 year warranty, but since most of these companies don't last 10 years, I am not sure what that is worth. I spend many hours a week on the phone dealing with problems that could have easily been avoided with a little extra effort on the front end rather than chasing problems that have been seen thousands of times and are nothing new, the old saying still applies, a Penny saved can cost you thousands.. I may have changed the old saying slightly but I am sure you get the point.

 

[LLigetfa]

If you have ever shut off the water at the pressure tank and noted how much pressure is stored in all the plumbing downstream of the valve when bleeding off the pressure, that is the same volume that could reverse flow through the softener. If you have an irrigation system before the softener, there can be reverse flow when the sprinklers come on. Even if it is not enough for the reverse flow to run hot and do damage, it can still unsettle the media pack and affect the performance of the system.

Any time I purged the lines going to the iron filter and softener, it disturbed the media pack and I had to then run a manual regen to pack them.

 

[ditttohead]

Hot water backup.

 

[Tort]

This forum is great and really appreciate each comment /discussion point. I am learning a lot. Thank you. I kept reflecting on the comment Reach4 made about adding more pipe. I am liking that idea more. To recap the situation, I need a minimum of 10' pipe between the softener and water heater. There are about 6-7" feet of existing 3/4" copper pipe now. I figured out a way to add approx 5 feet of 3/4 copper pipe and hide it on the wall behind the softener. If successful, it may eliminate the need for check valves and thermal expansion tanks. I have attached is a rough illustration. Does this concept have any issues or flaws?

 

[Reach4]

I you want to get fancy, there is a 3/4" x 2-1/2" Copper Return Bend.

 

[ditttohead]

LOL, why so much effort rather than adding a check valve and an expansion tank? The expansion tank has the added benefit of greatly reducing water hammer throughout the house. It is basically a huge shock absorber for your plumbing. The check valve will ensure that you don't have any hot water backing up into the softener and it will reduce the ghost meter readings that are common on modern softeners due to their highly accurate turbine meter designs. Here is the check valve I use for copper plumbing. A few dollars more than the cheap ones but I did mostly commercial work where these things take a beating.

https://www.zoro.com/apollo-ball-cone-check-valve-bronze-1-fnpt-6110501/i/G0936835/

The Amtrol ST-5 is a good thermal expansion tank and should be adequate for your application. The ST-8 is what I usually recommend since it is only about $15 more.

 

[Reach4]

LOL, why so much effort rather than adding a check valve and an expansion tank? The expansion tank has the added benefit of greatly reducing water hammer throughout the house.

Thermal expansion tank is a point of failure, for one. If the 44 gallon pressure tank fails, I would notice. Thermal expansion tank would often be missed as a point of failure.

And I guess a check valve could fail to, and detecting that one leaks backwards would be hard, even if I were looking for it.

I have no water hammer now.

But then I don't have a vacuum breaker for my softener in my basement either. Living on the edge.