Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Munchkin F05 & Pr0 codes

ejm Member Posts: 6
Thanks for the response...

So for the F05: have not heard a sound yet. When the code is reset, the unit will reset itself and go back up to temperature and operate fine for a couple days, maybe a couple weeks. The plumber cannot get the code to flash when he is there. So I guess you would call it intermittent, because it will run fine for some time then kick back out. This is both when the heat for the house was on (in winter) and even now with just heating for our hot water.

And for the Pr0: There are no visible leaks anywhere near the unit or at any other pipe at or around the boiler. The pressure valve on the outlet always reads 10-20psi (the blue pressure guage).

-- Eric


  • ejm
    ejm Member Posts: 6
    Munchkin F05 & Pr0 codes

    We have been having both of these error codes now for about a year, since the 80m was installed in our new house. The plumber has been back about 6 times already. I have looked on the forums for more information about these codes but did not find anything that has a cure for our problem. The F05 error code we can at least reset, but with the Pr0 code the unit will not reset. When the Pr0 started, it would reset itself after a few hours. Now it stays on until the plumber comes. I'm loosing faith in the plumbers ability to fix this unit and am really tired of no heat or cold showers. We do not have the vision 1 outside temperature sensor. We are using natural gas. The munchkin is working with the smart storage (40 gallon) tank.

    Any help would be appreciated,
    -- Eric
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
    No flow and pressure problems.

    The F05 code is normally due to a problem with flow. If you don't have flow the temp in the boiler is going to sky-rocket and sound like someone is hitting the side of it with a ballpeen hammer. Check the pump.

    PRO is a water pressure switch. The boiler needs 10 PSI inside it at all times or this code will pop up. Are there any visible leaks in the piping that you can see? Any unexplained puddles on the floor under or around the boiler? Fix the leak and the pressure should stay in the boiler.
  • WaterHeaterGuy
    WaterHeaterGuy Member Posts: 80
    Quick diagnostic test

    If you push and hold the S4 button you will get a d1 alternating to a value. This value is the supply temperature sensor. If you tap the S4 button one more time you will get a d2 alternating to a value. This value is the return temperature sensor. If you keep tapping S4 it will cycle you up to d6. This is the RPM (x10) of your blower.

    An 80M boiler should be running about 460 on the d6 display for high fire, and about 200 for low fire. If your flows are correct and the boiler is at high fire you should see a 20º difference between d1 and d2. If you are running at low fire there would only be a 5º difference.

    If you can get this information it will help me determine what sort of flow we've got moving through the boiler.
  • ejm
    ejm Member Posts: 6

    i will get that to you... problem is right now the boiler has been locked down in the Pr0 mode (since Friday). Numerous messages went unaswered until this morning, still waiting to have someone come. Any idea how to get it off the PrO code? Cutting the power and the reset button both do not work...
  • Rob L_4
    Rob L_4 Member Posts: 5
    Faulty Pressure Switch?

    I had a customer with something similar.
    Maybe something is wrong with the water pressure switch causing the PRO code. check the wiring, try adjusting the center knob counterclockwise to close it. If pressure is above 10 psi it should close.
    After this you could try to "jump" out the wiring as a temporary test and if closes and boiler works you might want to replace the water pressure switch
  • hr
    hr Member Posts: 6,106
    Is the boiler circ

    pumping into the boiler? It could be the circ is on the supply side and drops the boiler pressure below the 10 psi needed to make that pressure switch.

    Does the boiler have an accurate working pressure gauge?

    A basic continuity meter would be best to check that pressure switch. I'd hate to see you change the setting on it by adjusting the center screw. It's in there to protect your boiler from dry firing.

    Does it have an additional low water safety switch?

    hot rod

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • jalcoplumb_7
    jalcoplumb_7 Member Posts: 62
    Have you called the MFG?

    Have you called HTP tec. support? The number is listed on the web site.


    They do a great job.
  • ejm
    ejm Member Posts: 6

    Haven't called HTP yet. I'm willing to let the plumber fix the problem, or at least try. It's just getting to the pont where he is running out of things to look at and or fix. He is going to order a new part and see if that fixes the problem (i think the pressure sensor). I'm going to keep my eye on it afterwards to see.

    -- Eric
  • jalcoplumb_7
    jalcoplumb_7 Member Posts: 62

    Can you post a picture of the piping and pumps.
  • ejm
    ejm Member Posts: 6

    I will try when I get home.
  • Kevin G_3
    Kevin G_3 Member Posts: 7

    Where are you located. you should have you contractor contact his local sales rep through the supply house he purchased the boiler from.
  • Ted_9
    Ted_9 Member Posts: 1,718
  • ejm
    ejm Member Posts: 6

    no pics yet, sorry... very busy right now. The plumber should contact the local rep, I agree. But the technician is supposedly trained to install these so he keeps coming back. I guess its easier to send your guy than to call the manufacturer and get the job done right. I don't know.
  • ChathamBrewing
    ChathamBrewing Member Posts: 1
    Bad water pressure switch

    After reading the post and doing the quick test to bypass the switch, I found that the switch was "bad"....So I went and got a new switch ($85) ... And, removed the old switch to find a bunch of gunk (technical term) in the business end of the pressure switch. after some scraping and poking and cleaning, I re-inserted the switch and it worked! Returned to unused switch (saved $85) and now have a functioning boiler.

    So, if you are getting the Pr0 code and are certain that the pressure is up, pull the switch and clean it. It might just work again...
  • tim smith
    tim smith Member Posts: 2,738
    Munchkin problems

    Your plumber needs to call tech support while on site to go over the on going problems. They are very helpful, they have buckets more tech knowledge from all the calls they can than anyone. They will help him get you back on line much faster than on his own.  The plugged pressure switch port is very common on systems that have been converted. Needs to be cleaned during annual maintenance along with lwco probe, igniter and heat exchanger. Do this and unit will be more reliable.
    STEVEALMC Member Posts: 1

  • Steve Whitbeck
    Steve Whitbeck Member Posts: 669

    Take a bunch of pictures of the boiler, the pumps and all of the piping and put them on here or send them to [email protected] and WE or I will try to help you.
This discussion has been closed.