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has anyone changed a diaphragm on the water valve of a Aquah 16L tankless water heater?

 
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Before we call our plumber I thought I would ask here...
this is the link to the water heater
We are fairly certain the problem has been the diaphragm.  The water heater has been in use for four years and our water has a lot of scale even with a whole house filter preceding the water heater.  The trouble shooting symptoms all pointed to that.

We have the new diaphragm and the Aquah guy says we don't need a plumber, just take off the water valve.  Well it is not at all that straight forward...there are lots of things to disconnect, more than George has told us and he does not have a schematic...he says for us to call him for more help.....or to have the plumber call.

Steve is good at things like this but it looks like he would practically have to take all of the innards apart to get the water valve out and we are wondering if there is some other approach that is not apparent?

I'm somewhat annoyed that a part like that would come with no instructions?
This is the 'water valve assembly' that needs to come off of the heater and be opened up to replace the diaphragm

https://aquahstore.com/catalog/product_info.php?cPath=25_39&products_id=98

I've probably attached too many photos

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Hi Judith;
I have not changed the diaphragm on an Aquah, but I did on my Paloma PH -6 . Once you have access to the valve its simple, and straight forward. Getting too the valve is the knuckle skinning part.

Yours looks very similar.  Mine has a standing pilot light, so no wires at all. I have no clue what the larger three black wires are coming from the top to the left or, if they are wires at all.

From what I can see, the yellow line is the propane regulator. It will need to come off. (sounds easy right... I hope/ but doubt it will be) After it is moved aside. The silver up pipe will need unscrewed/removed.
At that point it may??? be possible to leave half the cold water valve attached. Unscrewing the cover leaving the back in place??
If not, it appears that not to many more screws need come off, to get it free of the frame.
Once you have it in hand, installing the diaphragm is nothing.

Sorry I don't have an easy fix idea for you.  Mine looked daunting until I started... then as each part came off the next would be apparent how it came off.
I'm confident that Steve can do this. Take pictures as each part is removed.
I mean after all, he is not building a RMH ... so no rocket science needed :)


 
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Judith,   I havn't replaced a diaphragm on your model either but have on our tankless Bosch heater. On ours, the diaphragm is located right at the joint where the two halves of the water valve assembly (WVA) come together.

Another take on Thomas' take-apart-tutorial based on your photos:

Be sure to check with step 4 first before continuing...

1)Turn off the propane, water and possibly power breaker to the tank.
2)Drain the water out of the tank by opening the drain valve on the WVA
3)Disconnect the copper line going to the WVA (on the right side)
4)Remove the 5 phillips head screws/bolts that hold the two halves of the WVA together (assuming you can access them all ?)
5)You may not have to disconnect the cold water inlet line which is PEX line and can flex somewhat, but at this point, the two halves of the WVA should separate and that's where the bladder should be to replace.  Good luck!

EDIT:  You mentioned scale. Have you checked the pre-filter to see if its clogged? If I had to guess, I would say it is located on the brass stem where the water inlet (the blue PEX line) is attached to. It is usually a long tube filter that is kinda wedged in there and is a little tricky to pull out.
 
thomas rubino
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Good point Gerry!  
Mine has a small screen pushed into the cold water side. It plug's up and then heater operation becomes erratic.  
It still works but if you turn down the hot valve a touch to much... it will shut off.  No fun while in the shower, where the cold water side is in the lower 30's all year long.

Judith, I know you have a prefilter, but you could still have another at the heater...   worth checking before you dive in.

 
Judith Browning
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Thank you both!  

For some reason the Aquah guy directed us towards the diaphragm...Steve had originally asked him about the filter/screen on the incoming water.

Will check that first.  
 
Judith Browning
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4)Remove the 5 phillips head screws/bolts that hold the two halves of the WVA together (assuming you can access them all ?)
5)You may not have to disconnect the cold water inlet line which is PEX line and can flex somewhat, but at this point, the two halves of the WVA should separate and that's where the bladder should be to replace.  Good luck!  



'assuming you can access them all' ...and that is the problem.  It looked like changing the diaphragm would be just that straight forward but the screws were impossible to access without removing many other things.  
 
Gerry Parent
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Sometimes if there is enough room to accommodate one of those small phillips head bits (from a multi-bit screwdriver), then with a pair of pliers grab onto it an turn it, can work too.
I have one of these tools that has gotten me out of trouble more than once that look like this:

 
thomas rubino
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Hi Judith;
I'm hoping you find a dirty inlet screen.
I'm curious what the complaint is about your heater ?
 
Judith Browning
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thomas rubino wrote:Hi Judith;
I'm hoping you find a dirty inlet screen.
I'm curious what the complaint is about your heater ?



At the moment, for it to kick on at all, we have water flow turned as low as possible and the gas itself up a little from what was normal for years.  

In order to get hot water at the kitchen sink we have to have another faucet running.  The washing machine hot kicks on and so will the bath tub on their own because they have a heavier water flow.  To take a shower and keep the hot flowing we have to have the sink running at the same time.  We're wasting a lot of water at the moment.  Until we figured this much out, the hot was shutting itself off during a shower and we couldn't get any hot to the sinks....I'm probably not explaining it very well but we got to this point through a lot of adjusting and testing different combinations.

The first thing Steve asked about at Aquah was the inlet screen and for some reason the guy thought we needed a new diaphragm.

We also had the cover off and cleaned all the dust, etc out, checked the burners, replaced the 'D' cells, ran vinegar through the system...

Until the last few months, it has worked great and steady at a certain setting.  Over four years we had pumped vinegar through it twice and not done the other cleaning, so it's definitely time to catch up with maintenance.

 
thomas rubino
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Well its worth a look at the screen. From your description its hard to say, it very well could be the diaphragm.

 
Judith Browning
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Checked today and unfortunately, the inlet screen was clean...we were hoping for some glaring gunk there, but no.

onward...

 
thomas rubino
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Hi Judith ; Thanks for the update.
I thought about your heater, just this morning! Wondering if maybe a screen cleaning worked for you!  Bummer that it didn't!
I'm still sure Steve can do this.  Like any mechanical job , it looks bad , BUT as you dig in, things generally become clear how to proceed.
Good Luck!  Let us know when you get it working well again.
 
Gerry Parent
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Judith Browning wrote:The water heater has been in use for four years and our water has a lot of scale even with a whole house filter preceding the water heater.  The trouble shooting symptoms all pointed to that.


The scale you mentioned keeps coming back to me. Have you checked your whole house filter lately? It could be that its getting plugged and slowing the water flow enough to not trigger the heater anymore or the heater itself is getting a scale buildup and doing the same.


 
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"At the moment, for it to kick on at all, we have water flow turned as low as possible"

Judith.  I have this water heater and also a pre-filter setup.  Have you checked the incoming PSI on your water? The Aquah is designed to automatically shut off if the water pressure isn't high enough.  When was the last time you checked your filters on the pre-filter system?  Perhaps also, maybe there is calcification at some point in your pipes and the water pressure is different at different places in the house.  I have 8.5 water here, and I have had to replace one tankless after another.  I finally got so tired of having constant problems that I just disconnected them from the pre-filter systems and have them on their own dedicated pipe systems on 5 gallon propane tanks.  In regards to the Aquah guys, they are really really nice, they helped me with a problem where I made a big mistake and they didn't have to help but went way out of their way to help me resolve the problem I created. That said, I seem to have communication problems with them whenever I talk with them.  We never seem to be on the same page - LOL.  
 
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Just for information, scale is from dissolved minerals in the water. It can't be filtered out. You would need a water softener installed to lower the mineral content in the water.

Had a similar problem with an old tank-less water heater.Home owner decided to up grade the heater. Wan not easy to change out the systems. Required replumbing to adapt the new heater.
 
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Judith,
Just start taking things apart until you have the diaphragm valve in your hand. Then, and only then, remove the 5 screws on the cap.  Be very careful when you take apart a connection made with bolts or screws because there is a fragile gasket in there that needs to be reused. I wet the gasket with plumbers grease or a silicon lubricant.  Not too much, just wet it.
I have never had luck with vinegar to de scale the coils.  Try a de scaler specially made for tankless water heaters.  Home Depot and Lowes have them.  also some tankless heaters must be plugged in and turned on for the modulating valves to open allowing the circulation of the descaler.  Keep the gas off.
A phosphate feeder in the cold water supply may help keep the minerals in suspension as they pass through the coils.  Some swear by the magnetic affect when two permanent magnets are bolted to the supply line.  They are sold as a kit.
Another thing with tankless heaters is to set the temperature low and if possible shower with hot water only.  We used to call them flash heaters and each person would set the temperature they liked when they showered.
 
Judith Browning
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Thanks everyone...

We change the whole house filter monthly...more often than recommended.

The heater has worked great for four years, until the last six? months.  

We are adaptable so because we could keep it functioning with a few tweaks we're slow to fix although I know we are wasting water.  The hot shower is still working as long as the sink faucet is running at the same time...and it used to work perfectly set at a certain level of gas and water flow according to the temperature of the incoming water, seasonally.

We have municipal water and really good pressure...that was one of the first things we looked into when we bought the water heater.  I don't remember the numbers though?

The filter was good, we have the new diaphragm here ready to go but thought we would try the vinegar again and then backflushing through the diaphragm in case it is clogged and not worn out (stiff?).  Have not looked into the commercial descaler stuff? Might need to....

Thanks for all of the input...very helpful!

 
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well i have had a few different cheap/older tankless hot water heaters that had quirks....so possibly what i went through with one could be related. for me with one it was the pilot...where the small part that was where the pilot light went on got ??? clogged with funk ??? or something, and taking this off and giving it a long soak in some strong cleaner stuff my friend hooked me up with..."fixed" my old hot water heater...where it stopped going on and off.

well yeah, no idea if this is your issue, and maybe not since you say it's related to not getting enough pressure and having to turn the sink on...hmmm...but, worth a thought anyway...if it's not the pilot/gas line flickering. those hot water heaters can be finicky. i've used several and almost all of them did that every so often...which SUCKS when your showering and suddenly get cold...although it was usually ok and only doing that every once in a great while isnt bad.
 
leila hamaya
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one other thought, which may or may not be relevant, is that if you found out it is the related to the water pressure you could get a pressure tank. this would well cost money and be a chore...but i have also lived with really bad low pressure water and a finnicky tankless heater...and my landmate at the time got a pressure tank and this immediate worked out with the issues the hot water heater was having, cause it evened up and seriously upgraded the pressure.
 
Judith Browning
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hi Leila, great to hear from you! Haven't seen you around for awhile?

The water heater has a battery powered electric ignition so no pilot light and we've switched out the batteries so they are fresh.

The water pressure is fine, we checked it when we installed the heater and it's worked great until about six months ago.

thanks though!
 
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yep, well worth a thought. stuff like that is always so tricky to figure out. best of luck.

and yeah i've been offline, working a lot, "gone dark" for a while! am getting tons of stuff done though...
 
Judith Browning
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checking here first to see if anyone has tried this:

1) Wash the diaphragm clean by pumping pressurized water though the water
outlet (hot side) into the water heater  

What is not explained is if 'pressurized' water is just a faucet through a hose pressure? and if the water needs to be draining through another hose on the cold side while being run through the diaphragm?

We are having one of those series of breakdowns on 'stuff' so have not got back to this one as we can still get hot water.
Of course, the breakdowns are coinciding with company coming in a couple weeks



 
Judith Browning
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This is the conversation he's had so far with the company...very friendly, and seemingly helpful but maybe not on the same page as someone mentioned above?

steve says...I have a service question about our 4 year old Aquah 16L (propane):
Its ignition has gotten very irregular-- it either doesn't kick on at all,
or does and then shuts off in1-3 minutes, occasionally 5 or 6. And it
usually requires two sinks to be running to kick on at all. Can this be the
"inlet water filter screen"? We have a whole house filter, changed
regularly, before the water heater, but the inlet screen has never been
checked. Is it something I can do, or does it require a plumber?



.....Hi Steve,

You do not need a plumber. It appears that the diaphragm in the water valve
is either dirty with mineral deposits on its surface or the diaphragm has
gotten rigid over time. As a result, it does not yield to the water pressure
as well as before and that is why you need to turn two faucets on for this
unit to kick on.

You can do two things:

1) Wash the diaphragm clean by pumping pressurized water though the water
outlet (hot side) into the water heater or you may clean the diaphragm up by
taking the water valve apart; or

2) Replace the diaphragm.

You can still get along with the current diaphragm for the time being but
you will need to clean or replace the diaphragm eventually:

Turn a faucet on. If the unit does not kick on, with water running, turn the
Water knob on the front panel clockwise gradually, and the unit may kick on
at a certain point. If the unit kicks on, turn the knob a little bit further
to make sure you have more than enough water pressure to activate the heater
next time. You may need to reduce the gas flow a little if water gets too
hot.

Thanks! If you have any more questions, please let me know.



steve....I ordered and received a diaphragm for our 16L propane.  You said I don't need a plumber, so I take it I can change this out myself.  I just wondered if I'm going to get it apart and then find out I need some gasket or special gunk to put it back together.  Any advice on the job?



.....Just take the water valve off of the water heater and take it apart. You do not need anything else. Just replace the diaphragm. Also, when you put the water valve back after you replace the diaphragm, make sure to put the rubber seals in place. Thanks!



steve.....
I concede defeat.  I am unable to "just take the water valve off the water heater."  Even if "water valve" means just the right half of the "water valve assembly", the five screws still go in from the inaccessible left.  And even if I remove the solenoid to get at one hidden screw, I can't reach another without tearing into the electronic heart the solenoid is wired to, and even then I think the whole gas manifold is still in the way.  I couldn't even loosen the incoming water connection.  I'm calling the plumber.  Please send diagrammatic instructions for him.  (He has some experience with on demand water heaters.)



.....Hi Steve, I tried to call you but nobody answered the phone. Left a message in your voicemail. I don't have instructions on replacing the diaphragm. Please ask the plumber to call me when he has questions. By the way, it appears you did not do it right. You first need to take the water valve off of the water heater. Then take the water valve apart to replace the diaphragm. You cannot take the valve apart when the water valve is on the heater. If you wanna try again, call me. Thanks!  



Since then, Steve has got at the filter and it was clean.  and we're looking at flushing the diaphragm as mentioned in my previous post.  And I wonder who's voice mail got the message as we don't have an answering machine nor voice mail

We really love this water heater and have had no problems until  recently.

 
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