Problem: Many of us with on-demand water heaters have experienced the problem of getting hot water at the tub but not at the sink. We waste water and get the E1 error code since there is not enough water flow at the sink to activate the water heater. Why this condition exists is explained by the factory plumbing.
The on-demand water heater in my 2023 Jayco 195RB is activated by water flow and that is volume not pressure. One can have great pressure and poor flow a water nozzle is an example.
The water pump and water pressure regulator are assumed to deliver a constant volume over time of 3 GPM at 45 PSI so the only thing one can change is the flow restrictions in the diameter of the piping and reduce the number of elbows and tees.
The cross-sectional area of 1/2 inch ID Aqualock Fitting - .79
The cross-sectional area of 3/8 inch ID PEX Fitting - .44
Each elbow reduces the flow by about 5% at a minimum and I had 5 3/8 ID PEX elbows or tees between the pump and the kitchen faucet so that was at least another 25% reduction.
The following photos were of the plumbing the factory installed.
Before: As delivered from the factory there are a lot of elbows and tees restricting water flow. Plumbing was designed for easy assembly, not water flow. Those of you with E1 errors low flow is the cause of the error.
After: Two mini manifolds purpose-built from Watts Aqualock push to connect fittings with stackable tees and PEX-A. Remove the inlet screen from the water heater which blocks flow. The screen is unnecessary, and there is one at the pump and one at the city water inlet already, so it is redundant.
Tips:
Watts Aqualock doesn’t reduce the ID to 3/8 inch like PEX crimp fittings do, you get a full 1/2 inch ID.
Using Watts Aqualock stackable tees one can make a mini manifold reducing the number of elbows and increasing flow.
Doing a retrofit in a tight space is only possible with push-to-connect since you can’t get a crimp tool in there.
Used bend supports instead of elbows to make turns, easy with PEX-A
Insertion of the PEX tubing into the fitting works better if you put the PEX insert into the fitting first past the collet. Depending on the alignment of the tubing with the fitting the insert can get hung up if you put it into the piping before insertion.
Watts Aqualock comes in and wait for it… barbed hose to PEX connection the 3513.
I didn’t use personally this as it was not available locally. I opted for brass 1/2 inch barbed to 1/2 FIP then converted using Aqualock 1/2 inch MIP to 1/2 PEX, these connections take Teflon tape only. You can’t use pipe dope with these plastic fittings.
More information about Watts Aqualock at
https://www.watts.com/aqualock
Performance:
Water heater lights immediately at 50% faucet in the kitchen. Low lag time to hot water since run lengths are reduced. Works like it is supposed to. Success!
Linear Mode
