Dema float valve 437N keeps failing

[stampedecarwash]

Hello I have had this valve for atleast 5 years now. Once a year it failed to stop the flow so I changed the diphram and spring inside it ($10 repair kit) and it was good for another year. Now it fails every two month. I changed my water heatr 6 month ago and increased my hot water temperature to 130F vs 120F it was before. Is this why it fails? The spec says it should be good until 140F. Perhaps the repair kit is not a good batch? Is the temperature too high?
This valve is inside the hot water tank on coleman hanna super Savor system.

 

[Toms PTcarwash]

Do you have good quality soft water to the valve?

 

[stampedecarwash]

Do you have good quality soft water to the valve?

Yes we do and we check the quality of our water every week…. Im thinking to change the whole thing after 5 years now lol. I just dont know if it fails again after 2 months even with the new one

 

[stampedecarwash]

One more thing, when opned it today didnt see this number 9 little part in it (see pic) so didnt put it, perhaps thats why it failed so fast??

 

[Dan-Ark]

Ive had some problems with one similar dema valve. would randomly stay on and mix tire cleaner until it ran out the back door (this wash has no floor drain). Would do it about once every week or two. Played with it a few times, decided to replace the whole thing. I noticed it was a little off level and the weight was pulling slightly on one side, did some adjustments trying to save chemicals till the new one came in. That was a year ago, apparently having a new spare on the shelf is all that was needed to solve the problem. The new one is still there, on the shelf, doing its job. Have a compressor motor sitting in its box at my other wash doing the same ...

 

[Earl Weiss]

One more thing, when opned it today didnt see this number 9 little part in it (see pic) so didnt put it, perhaps thats why it failed so fast??

It won't work without that part. It must have fallen out when you did a re build. I have also had the spring fail every few years and had to replace it. FWIW I do a rebuild twice a year as preventive maintenance.

 

[stampedecarwash]

It won't work without that part. It must have fallen out when you did a re build. I have also had the spring fail every few years and had to replace it. FWIW I do a rebuild twice a year as preventive maintenance.

My mistake, that part is actually there. I opened it this working and it was there. I did change it to the new one from the kit, but dont think it helps much, it doesnt look like a part that wear out easy.

 

[MEP001]

This is the reason I won't use these or the Hydrominder equivalent. I've tried them both multiple times over the years and always had a similar problem. If you can switch to a regular float valve, I recommend the Walters/Watermaster. I use the 1" because it has a stainless steel seat insert. I've never had one fail to open nor had one hang up wide open. They do need to be rebuilt with a new diaphragm every 1 to 2 years, but worst case it will very slowly overfill the tank.

 

[Kevin James]

We've had really good luck with the Jobe valve. https://www.kleen-ritecorp.com/p-27147-jobe-1-topaz-industro-hi-temp-float-valve.aspx#description We tried the DEMA 437 once and had the same problem your having.

 

[Earl Weiss]

Since using the 573 Hydrominder unit and doing a PM rebuild twice year - no issues. Walters Hudson and Jobe have all failed on me I have stuck with this one. Keep a spare on the shelf and swap it out twice a year, and rebuild the old one and that goes on the shelf as the spare.