No hot water pressure - hybrid water heater with thermostatic mixing valve

We lost all water pressure on the hot side of our house plumbing while cold remained at full pressure. This video is of disassembly, diagnosis, and repair of the thermostatic mixing valve that I installed on our A.O. Smith heat pump water heater. This video also includes my opinion and review of the water heater and of a thermostatic mixing valve.

[@dus10dnd]

If that screen is stainless steel, you don't want to be using a wire brush or scrape it with a screw driver. The galvanizing process is generally done at only a surface level which means the abrasiveness will scratch it deep enough to get past the stainless and that thing will now rust. Using some CLR on it would be appropriate. Also, that water heater will certainly save you some money. The other thing to consider is to look at your rate schedule from the utility and see if you get different rates based on time of use; you can program the water heater to operate when your electricity rate is the cheapest. I have my water heater on order (I got the AO Smith 80-gallon 120V system because we're replacing a gas water heater), but I installed the AO Smith 50-gallon 240V unit for my daughter a couple of months ago and there is still some learning to do about the settings. She has no TMX and she takes long showers, so I plan on adding a TMX and a thermal expansion tank so they can increase their temperature up to 140F and not run out of hot water. I have replaced my air conditioner with a Mr. Cool Universal heat pump and I am planning to replace my washer/dryer stack (that we just replaced in 2022) with one or two of the LG combo units (single unit is both a washer and dryer, but the dryer is a heat pump dryer). Once I do that, I am switching my electric service to a time of use plan which will save me even more money for off-peak usage. Our standard plan still gives us a 20% discount for off-peak usage, but the time of use plan reduces all usage to a 20% discount, and then we get a 50% discount for "super off-peak" usage and a 3x premium for peak usage. So, by telling the unit to get up to 140F temp during super off-peak and to never run during peak usage (maybe telling it to maintain 120F during normal times), we will save even more money. We'll be saving money no matter what because our gas unit has a forced air vent that consumes 376W of electricity and I have a portable AC that I use as a dehumidifier in my basement that runs at about 900W... so the new water heat will handle both tasks for me and I will be able to shut off my gas service which has a monthly $30 fee just to have the service active, let alone usage fees on top of it.

[@MajorDadsGarage]

Thanks for the tip! I need to remove it again and will use CLR next time.

[@dus10dnd]

@@MajorDadsGarage I also wonder if you changed the orientation so that it is vertically oriented if it would prevent the debris from getting into the screen.

[@bj7859]

Prior to the clogging issue, did you find that your hot water pressure was affected by the mixing valve at all? Also, how long did it take to clog? I didn't catch the timeline. Thank you for the video. I'm building new and have decided on 2 x 50 gallon Rheem hybrid water heaters in a conditioned/sealed attic in the south

[@MajorDadsGarage]

Prior to clogging we had no water pressure issues. I just had to clean it again so it clogs in about 3 months. I contemplated removing the screen but used a pick tool to make 10ish slightly larger holes. Seems to have done the trick.

[@CWBKC]

might need to put a sediment filter followed by a charcoal filter before your WH. Also, it looks like your MV necks down to like 3/8 when you reinstalled the washer, that's not good when it comes to pressure. I think maybe you should look into a Watts MV from Supply House and stop buying everything from the box stores. One more thing, clean the old tape off your threads.

[@MajorDadsGarage]

Thanks for the tips! I would like to put a filter on the cold inlet from the street but I’m not sure where it comes in because it runs under the slab. I’ll look into your other tips!