Stuck Diverter Valve (Lochinvar Noble Combi)

anonlineuser

I have a Lochinvar Noble powering DHW as well as my heating (hydro air). While DHW is functioning as expected, hot water does not flow to the air handler (pipe remains cold). It's the start of a cold spell here, so the heat hasn't been used in quite a few months.

This has happened before, and the HVAC company told me the diverter valve requires servicing during annual maintenance.

I'm wondering whether there is anything I should be doing proactively to prevent this from happening, whether the HVAC company is correct here, and whether there is anything I can do myself to "unstick" it.

hot_rod

you might add some service valves to the water connections. Then you can attach a clean and flush kit once a year. The minerals in the water can cause the valve and plate heat exchanger to get scaled up.

The kit includes a chemical, bucket, hoses and pump got the procedure.

If this is something you want to tackle on your own?

GGross

Flushing the DHW side of the flat plate will not touch the water on the diverter side.

Some things I have seen first and foremost the water quality on the boiler side of the water, if you have leaks, or add too much makeup water, or have sludge or scale issues on the boiler water side that will negatively impact the diverter, some can be fully removed and descaled though paying a pro to do this will not be cost effective.

It's possible a vacuum develops that prevents the diverter from moving, this is much harder to diagnose and to solve

sometimes you can manually remove the diverter actuator, and operate the valve to a center position, flush the boiler water like you were purging air, and set everything back up and it works. this may or may not work on this style of diverter. this can be done without removing the valve body from the system, its easiest. if this is a recurring problem you may want to schedule that service for the middle of the "off" season, or learn to DIY it. on the style I am familiar with its as simple as removing the actuator and pulling up on the valve stem, if you have purge points to isolate the boiler its no more difficult than purging a boiler like you would on install.

Power cycling your boiler periodically in the "off" season may be enough to keep the valve unstuck, typically these valves cycle themselves on power up. the DHW position is usually the default position which is likely why it gets stuck there. during heating season at every call for heat, and after every call for heat, the valve will move.

as for your contractor saying the diverter needs service, while they don't all need service its apparent that yours does need it.