[RESOLVED] Reduced hot water flow after installing mixing valve

[DIYinATX]

EDIT: I'm a dummy. User error, most likely.
See post # 11

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Hi Folks,

I installed a Watts 500800 Recirculation Pump onto my 38 gallon electric water heater in my house.
This setup has been working okay but I'm running out of hot water when filling my 80 gallon jacuzzi.

So, I then purchased a Honeywell AMX300TLF mixing valve and a Honeywell L6006C1018 aquastat controller.

I haven't installed the Aquastat yet but I did get the AMX300 mixing valve installed last night and I disconnected power to my recirculation pump until I get the aquastat installed. You can see in the pic below the water heater tank--> mixing valve--> recirculation pump.

I then cranked up the heat on my 38 gallon tank to the max and set the mixing valve to where hot water coming out of the faucet is about 115*F.

Problem is, I have very reduced water flow. When I first open the hot water, I get correct flow. But within seconds, the flow is reduced by about half.
What do I do to resolve that?

Also, did I buy the wrong Aquastat for my setup?
Not sure how to wire it up to my pump. All the wiring diagrams I'm finding seem to indicate an additional relay is required.
It also wants a dedicated return line but I won't have that installed for another year or two.

If I can get the kinks worked out, I plan to tidy up the install and put a 1" pipe where the flex pipe is.
And mount the aquastat to the 1" pipe. Like in the pic below.

This is all a temporary setup while I continue working on the rest of the house.

 

[WorthFlorida]

The high pressure at the very start is because of the pressure build up from expanded heated water. Is there an expansion tank? When water is not flowing the pressure is called static. It will be the same throughout the home at all fixtures and it starts with the pressure from the water supply. Heating water expands and builds pressure. Open a faucet (cold side too) and the pressure does drop some but the flow restriction is making seem worse than a normal pressure drop. Is the drop off of pressure or restricted water flow occur on the cold side? Did this start with the addition of the mixing valve?

From the specification sheet:

• Temperature is adjustable using push-twist-release locking hand wheel design and if cold water supply is interrupted, flow reduction occurs in seconds.

https://customer.resideo.com/en-US/Pages/Product.aspx?cat=HonECC%20Catalog&pid=AMX300TLF/U&category=AMX300%20Series%20DirectConnect%E2%84%A2&catpath=1.2.5.2.3&rank=1&v1=Sort.1.Product.Rank&asc=1


This is the brochure for the mixing assembly. It's quite nice with two additional ports on mixing side, #2 & #3. Check the description for #3 port. Perhaps a call to Resideo is needed. 1) The mixing valve may be reducing the internal dimensions of the 3/4 inch fitting reducing flow? 2) The circulator may be adding too much resistance to the water flow? Perhaps the circulator needs to be connected the port #3? The cross over at the water heater may be causing the issue since the mixing valve has a recirculated port. There might be a check valve built in.

https://customer.resideo.com/resources/Techlit/TechLitDocuments/67-0000s/67-7381.pdf

If you want the Aquastat to regulate when to turn on/off the circulator, you want is on the cold water pipe. With a two pipe system, warm water is pumped back to the water heater on the cold side. Once it reaches a set temperature, say 100º is when you want to shut off the circulator. I do not know if this is the correct aquastat to use.

Another is the flex hose of the T&P valve. It cannot go up hill. It must be level and down only. Should the valve open a little, water will lay in the pipe and hard water deposits and corrosion can eventually jam up the valve.

 

[Sponsor]

 

[DIYinATX]

Is there an expansion tank?
---Nope

Is the drop off of pressure or restricted water flow occur on the cold side?
---Cold side seems unaffected or if it is, it's not nearly as bad.

Did this start with the addition of the mixing valve?
---Yep!

I wonder if the mixing valve is restricting the hot water on purpose and it's a simple adjustment that I don't understand.

Thanks for the correction on the Aquastat location!

 

[Fitter30]

Here's a pressure drop chart mixing valve have a big drop. Then you have a drop going through the pump.

https://customer.resideo.com/resources/Techlit/TechLitDocuments/33-00000s/33-00443.pdf

 

[LLigetfa]

Then you have a drop going through the pump.

^^this^^ I think is the problem. The recirc is supposed to go to a dedicated side port.

 

[DIYinATX]

Here's a pressure drop chart mixing valve have a big drop. Then you have a drop going through the pump.

https://customer.resideo.com/resources/Techlit/TechLitDocuments/33-00000s/33-00443.pdf

^^this^^ I think is the problem. The recirc is supposed to go to a dedicated side port.

Thanks guys, but you don't understand.
This is a MASSIVE reduction in pressure.
I waited 10-15 minutes for hot water to dribble into my clothes washer yesterday.

Since nobody here is familiar with the issue, then I must have messed something up.
I'll start my troubleshooting by removing the pump later today.

 

[Fitter30]

Thanks guys, but you don't understand.
This is a MASSIVE reduction in pressure.
I waited 10-15 minutes for hot water to dribble into my clothes washer yesterday.

Since nobody here is familiar with the issue, then I must have messed something up.
I'll start my troubleshooting by removing the pump later today.

Look at page 2 of my link for the correct port for recirc

 

[DIYinATX]

Look at page 2 of my link for the correct port for recirc

There is no recirculation port being used because I don't have a recirculation line.
The Watts recirculation pump uses the "comfort valve" to send hot water back to the tank via the cold water line.

 

[DIYinATX]

Okay, I removed the recirculation pump and now hot water pressure is back to normal.

Using just the recirculation pump without mixing valve = normal pressure.
Using just the mixing valve without recirculation pump = normal pressure
But using both mixing valve AND recirculation pump = very low pressure

 

[WorthFlorida]

In the middle of night, I realized that #3 port is for the return side for a dedicated return line.

Okay, I removed the recirculation pump and now hot water pressure is back to normal.

Using just the recirculation pump without mixing valve = normal pressure.
Using just the mixing valve without recirculation pump = normal pressure
But using both mixing valve AND recirculation pump = very low pressure

Great!

 

[DIYinATX]

Hey, this may just be a user error thing.
Now that I know both devices work well individually, I went ahead and put everything back together.
So both devices are inline again.

Then, I went outside and turned back on the water line.
Came back into the house and heard an awful, loud WHINE.

Took a moment to realize that I'd left the vent valve in the open position.
Dogs were pretty concerned about all that noise.

Then, I turned the water back on incoming into the tank and tested pressure.
Pressure was normal!

• Temperature is adjustable using push-twist-release locking hand wheel design and if cold water supply is interrupted, flow reduction occurs in seconds.

Before I had been trying to figure out how I might have connected the lines wrong.
But now I'm wondering if I just never properly turned the water back on going into the tank.
I turned off the water valve and sure enough, my pressure dropped but I was still getting hot water.
Just not very much of it. Just like before.

So, now I'm okay on water pressure and just need to figure out the aquastat before I turn the pump back on.

Thanks folks. I apologize for taking up your time for a rookie mistake.

 

[Fitter30]

Pump should at the sink you have sensor valve for the whole line to be hot or if you mount the stat within a few feet could add a timer to let the pump run longer to heat the last few feet.

 

[Onokai]

I would go about this diffently-I used a grunfus smart pump

https://www.supplyhouse.com/Grundfos-99812354-10-Comfort-UP-10-16-High-Efficiency-Circulator-Pump-w-Digital-Timer?utm_source=google_ad&utm_medium=Shopping_withoutdata&utm_campaign=Shopping_Without_PLTV_data&gclid=CjwKCAiAqaWdBhAvEiwAGAQltnaFbBPusLfo3UszjXPRr2bozJdoA9KcJL0TYmuyL60IR8vq8iUaNxoCQtAQAvD_BwE

connected to the drain on bottom of tank and ran a line back from furthest faucet in house . This pumps leartns your usage and costs about $7 a year to operate. Hot water always when you need it. All in one device
You still need a recirculation line like my setup with one with one pump and no changes to in or out wtaer lines on water heater .
Not sure why the rest of stuff if you only want instant hot water
Maybe you are wanting more hot output from that 38 gallon heater?

 

[DIYinATX]

Yep, I mentioned in my original post that I was struggling to fill my 80 gallon jacuzzi with hot water.
That is no longer an issue with the mixer involved.

 

[Onokai]

Yep, I mentioned in my original post that I was struggling to fill my 80 gallon jacuzzi with hot water.
That is no longer an issue with the mixer involved.

So what does the mixer do in terms of more hot water?The mixer just ads cold water right ?

 

[John Gayewski]

So what does the mixer do in terms of more hot water?The mixer just ads cold water right ?

It protects the other fixtures from very hot water while keeping more btu's available to use. In theory one could just turn the heat up and run very hot water into the jacuzzi which will get mixed down in while in the jacuzzi, but any time any other fixture is used there's a danger of getting blasted with very hot water.

 

[Tuttles Revenge]

So what does the mixer do in terms of more hot water?The mixer just ads cold water right ?

The mixer allows the water heater to hold 20-30% more stored BTU by cranking up the heat, but mixing the temps back down to a safe to use temperature.

 

[Terry]

So what does the mixer do in terms of more hot water?The mixer just ads cold water right ?

They are to prevent scalding. Often the deck tubs will have a tempering valve in the bathroom for that safety reason.

 

[Onokai]

I use my tempering valve because I have a hot water solar system and it can generate really hot water in summer-that water flows froma 80 gallon solaraid Rheem tank to my 40 gallon gas water heater-then the hot water flows directly to dishwasher and the rest goes thru tempuring valve for scalding protection. What I do not get is why this may help fill a huge 80 gallon Jacuzzi tub? better with a 38 gallon electric water heater as OP was looking to do?I can see cranking up the temp would help a bit but the cost is high to do that. ands the differeance as noted maybe 20%? I would think a bigger tank would be the best way.

 

[LLigetfa]

What I do not get is why this may help fill a huge 80 gallon Jacuzzi tub? better with a 38 gallon electric water heater as OP was looking to do?

Its pretty simple really. If at a lower temp setting, the hot/cold mix is 50/50 then raising the temp changes the mix to use more cold for the same amount of hot. The alternative is to have a larger HWT.