Dishwasher water pressure issue

[rvluckyorwhat]

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]

Sure looks like a bend in there. HOpe it is that easy to fix.

[rvluckyorwhat]

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]

Look at the top 2 topics in the "Do It Yourself Modifications and Upgrades (DIY)" forum for how to post pictures.

Mike

[rvluckyorwhat]

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]

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]

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]

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]

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]

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]

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.

[rvluckyorwhat]

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.

[rvluckyorwhat]

Thanks Myredracer. Your post is very helpful. I had already replaced the filter yesterday (it was due anyway, although it looked OK) and checked the filter screen. It too was OK. The flow rate at my faucets was the same before and after I changed the filter. The dishwasher definitely runs better with the regulator, but some places I need one, so the pointer to a good regulator is very helpful. I ordered a pressure gauge online yesterday so when that comes in I will be able to see what my current regulator provides so I can decide then whether to get a new one.

The dishwasher definitely runs better when I don't use the regulator (which would be an argument for getting a new one).

However, I am seeing 1 gal/min at my faucets even with the regulator I have (I know I said 0.75 in the original post, but I since learned that my 1/2 gal bucket actually had a measuring line inside it and it was more than that to the brim), so if the DW only needs 0.65 gal/min, this would indicate that there is something wrong with the line to the DW or the DW flow sensing mechanism itself. It might be time to try to figure out how to pull the dishwasher out from my cabinetry to see if there is a hose kink or not.

[AllegroD]

What PSI does thor test your water lines at? 55 seems a bit low. Others had a great idea of checking your hoses and lines for kinks/blockage. Have you checked your water filter(s)? If dirty, each will reduce flow. Do you have any screens in the hoses/water intake which could be clogged?

[myredracer]

Getting a "real" regulator might help esp. one with a higher flow rate like a Watts 263A. I'd also mount a pressure gauge inside somewhere, possibly near the DW and see what the pressure does in a static condition and when a valve is wide open. Those exterior inline "regulators" aren't really regulators and are flow restrictors. Try removing it and see if the DW runs any better. You can modify PEX piping using sharkbite fittings and that way you won't need any special tools. Kinked lines are always a possiblity - we had a totally kinked one in our 2014 KZ.

Any RV should be able to run at 50 psi. I run ours at 60 psi because that's what the RVwaterfilterstore.com recommended to me. If you have any filters, check to see that they aren't plugged up and need replacing. The filter screen at the water inlet on the side of an RV can sometimes become clogged and also the check valve inside the water inlet.