Dishwasher water pressure issue

Ever since we bought our RV (new), we have noticed that the Fisher-Paykel dishwasher often is unable to complete a wash cycle. When it stops, it spits up a "U6" error code which indicates insufficient water pressure. I find that whenever we use our water pressure regulator outside (which is supposed to keep the pressure between 40-50 psi, the dishwasher usually stops. Without the regulator, it's hit or miss and depends on the RV park (and presumably, the pressure at the spigot).

I have been thinking about:
- buying a regulator that is set to 50-55 psi ($15)
- buying an adjustable regulator ($40, which would be worth it, but I've yet to find one with good customer reviews)

In the meantime, I called the manufacturer of our RV (it's a 2014 Thor Tuscany) and asked what the max water pressure is that they recommend. The customer service contact said don't exceed 50 psi. So maybe a more powerful or adjustable regulator isn't such a good idea after all. Next I called Fisher-Paykel and asked what pressure they require. I got a very indirect answer. They would not give me a pressure requirement (even though the error code says insufficient pressure). Instead they told me that the error I'm seeing will occur when the dishwasher can't pull 0.65 gal/min. Which sounded really low, but as an experiment, I measured flow through my kitchen sink and shower head just now with my regulator installed and they were only around 0.75 gal/min. The dishwasher has failed 5 out of 6 times that I've tried to run it at this location, meaning it ran to completion once. The other times, it would sometimes run for 10-20 minutes before failing, and sometimes would stop after 2-3 minutes. So I suppose I am at the cusp of what the dishwasher will tolerate.

I have also learned through measurement that my flow rate at my faucets doesn't seem to change regardless of whether I put the regulator at the spigot end or at the RV end of my 30 foot long hose, which kind of surprised me.

After all this, I decided to purchase a water pressure gauge so I can see what my regulator is providing, and also so that I can see what pressures seem to work and not work at various parks as we travel.

My questions are:
- Do others with Fisher Paykel washer drawers observe this problem?
- Have you found a solution?
- Do others have any other suggestions about what I might try? (besides the obvious --- "wash your dishes by hand")

Thanks!

AllegroD
Nomad
Mar 26, 2015
Sure looks like a bend in there. HOpe it is that easy to fix.
rvluckyorwhat
Explorer
Mar 26, 2015
Thanks. So when I reached up behind that wood panel you see upon which my dishwasher sits, here's what I pulled down from behind the unit:
mrgreetis
Explorer
Mar 26, 2015
Look at the top 2 topics in the "Do It Yourself Modifications and Upgrades (DIY)" forum for how to post pictures.

Mike
rvluckyorwhat
Explorer
Mar 26, 2015
By removing a couple of drawers (one below and one next to the DW), I was able to see just about all of the plumbing from the main water lines to the DW. I saw a small kink in the hose from the main line to the coupling into the hose that came attached to the DW. It did not look like enough to cause a problem, but I undid it anyway. I removed the coupling and saw that I was getting 2 gal/min of water through this hose! Then I reattached it and ran the dishwasher. It still failed.

Next I followed the DW's native hose up behind the unit with my hand because I could not find a good way to pull the unit from my cabinetry. Sure enough there was a HUGE kink in this hose! After cursing the installers at Thor under my breath a few times, I straightened the hose and I'm running the DW again. So far so good! Thanks for all your help. We took a picture of the hose before we straightened it. It doesn't appear that we can post pix on this message board, otherwise we would. I'm sure the photo will wind up in a blog or on our facebook page soon if you care to see the culprit.
dougrainer
Nomad
Mar 26, 2015
rvluckyorwhat wrote:
dougrainer:

-Of course I checked the spray arm first, which is why I never mentioned it.
-I've been talking about the pressure and/or flow being too LOW from the very start (not too high).
-While I agree 50 psi is probably CYA, going above it would not be covered should something go wrong so that is not my preferred route at this time unless I can find specs to support going higher.
-I agree that a hose kink seems like a likely culprit. I'm trying to figure out the best way to pull the DW from my cabinetry without damaging anything. It sits above a drawer, not directly on the floor. Any suggestions?

Look at the bottom on my previous post. That is the PSI that FP engineers stated to me just today. So, the problem is either a kinked hose or clogged hose. It is NOT easy on some DW to pull. Pull the drawer and make a stand to support the DW when you pull it. "Hopefully", they allowed extra line length to help pull. Doug
rvluckyorwhat
Explorer
Mar 26, 2015
dougrainer:

-Of course I checked the spray arm first, which is why I never mentioned it.
-I've been talking about the pressure and/or flow being too LOW from the very start (not too high).
-While I agree 50 psi is probably CYA, going above it would not be covered should something go wrong so that is not my preferred route at this time unless I can find specs to support going higher.
-I agree that a hose kink seems like a likely culprit. I'm trying to figure out the best way to pull the DW from my cabinetry without damaging anything. It sits above a drawer, not directly on the floor. Any suggestions?
dougrainer
Nomad
Mar 25, 2015
U6 U6 The spray arm has loosened or come off
its mounting, or water pressure is too
low.

You are hung up on pressure. From above, there are 2 things that can cause your problem. Water pressure is SECOND. NOT HIGH water pressure but LOW water pressure. The DW does not measure pressure. The system assumes if there is inadequate water to operate it is due to low pressure NOT supplying the needed volume. That points to a kinked supply line OR the hose supplying the Dishwasher has debris or something clogging the normal flow of water volume to the Dishwasher. To answer one of your questions. We have sold dozens of motorhomes with your Dishwasher and I have NEVER seen such a complaint. Doug

According to Fisher/Paykal engineers the LOW is 14.5 psi and the high is 145 psi for water pressure on their Dishwashers.
dougrainer
Nomad
Mar 25, 2015
rvluckyorwhat wrote:
Really AllegroD, 55 psi seems low? My manufacturer is telling me not to exceed 50, but now you and Myredracer are both suggesting a higher pressure.

ANY pressure an OEM states that is below 60 psi is a standard CYA statement. MOST RV water systems will hold at least 80 psi without problems. Years ago (40) we tested the Coachmen Trailers at 120 psi (air) for 30 minutes on the final production area of the line. Of course that was when ONLY copper was used:B Doug
rvluckyorwhat
Explorer
Mar 25, 2015
AllegroD wrote:
rvluckyorwhat wrote:
Really AllegroD, 55 psi seems low? My manufacturer is telling me not to exceed 50, but now you and Myredracer are both suggesting a higher pressure.

Yes. That is why I asked what Thor said. I do know that not all mfgr use same standards. So if Thor says to use 50, then I would not exceed their recommendation. I have a Tiffin Allegro 36LA. It is tested at 115. I use 65 on my regulator without fear or incident.

Nice! Lucky you!
AllegroD
Nomad
Mar 25, 2015
rvluckyorwhat wrote:
Really AllegroD, 55 psi seems low? My manufacturer is telling me not to exceed 50, but now you and Myredracer are both suggesting a higher pressure.

Yes. That is why I asked what Thor said. I do know that not all mfgr use same standards. So if Thor says to use 50, then I would not exceed their recommendation. I have a Tiffin Allegro 36LA. It is tested at 115. I use 65 on my regulator without fear or incident.

Forum Discussion

Dishwasher water pressure issue

About Technical Issues

Related Content

Water pressure regulator...

No water pressure

Water pressure issue

So who really uses the coach dishwasher

water pump and pressure issues