The check valve in the inlet connect from the boiler supply line is making the noise. To prove a point, put an ice cube on the radiant supply sensor which should make the injection pump speed up. If the noise goes away when the pump speeds up, then it is the check.
   To eliminate the noise, break the hot water supply connection and unscrew the adaptor fitting from the block manifold. Look inside that connection and you should see the check and a snap ring holding it in place. Remove the snap ring and then the check. Reinstall the adaptor fitting and re-splice the copper tubing.
   This noise problem has occurred once in a while and we are developing a new check that should overcome it. At this time, this is our only solution and I have not heard of any problem operating without the check.

We recommend the following sequence for cleaning and start-up of a LoadMatch® system:

1. Initially, start the primary pumps only. Leave the LoadMatch® secondary circulators off. This will ensure that you don't pump construction debris through the terminal units.
2. Continue to clean the start-up screens in the suction diffusers until the start-up screens are clean.
3. Start the LoadMatch® secondary circulators and continue to clean the start-up screens.
4. When the start-up screens stay clean, remove the start-up screens and turn the system to automatic operation.

1st you will need to go into the ADJUST menu and turn the Boiler Min setting to "off". Next, on the back of the control, you will need to put the toggle switch in the upper right hand corner to the "off" position. You will then need to unplug the unit, wait approx 15 seconds and turn the unit back on. Error should be gone.

If the pump is on a timer check that the clock is programmed properly. If the timer is set for on check to see if the pump is running by placing a screw driver blade against the pump casing and the hand to your ear. Turn the pump off and then on and listen for a cost down and speed up. If this is ok you have an air block in the return line. Shut off the valve between the pump discharge and the hot water tank. Hopefully the plumber installed a hose bib between the shut off and the pump. If not shut off the cold water to the hot water heater , loosen the motor bolts, place bucket under the pump, turn on the cold water and wait for the air to be purged from the return line through the pump. When the water is steady, shut off the cold water, check o-ring seating and reseal the pump. Reopen the cold water line and check for leak. Open the valve between the pump and hot water tank and you should have hot water.