Maybe an indirect is better

Le John

I have a Lochinvar Noble NKC 199 is a tenant occupied 2 family house. I was there yesterday and noticed the unit cycle on and off at least 50 times from people using the faucets showers etc. At one point the water pressure was fluctuating. Does that mean the flat plate has reached it max GPM?

The unit has run very well for 5 years(I do the maintenance on it yearly) but I was considering adding a 20 Gallon indirect to help with the on and off cycles from the DHW demand. Is this a good idea? If so what brand and model indirect?

Appreciate the assistance.

Hot_water_fan

If no one is complaining, I see no reason to. Combis short cycle, it’s their nature. An indirect or just a plain old separate tank are better products. 

hot_rod

Nice to hear the combi works out on a two family application.

You could add a bit of a buffer tank to lessen short cycles. Some of the tankless WHs now have a small tank inside to eliminate the"cold sandwich" and for some buffer effect.

A 6 or 12 gallon electric water heater would work also for less $$

Le John

@hot_rod would I be able to use the electric as an indirect?

hot_rod

Just a miniature version of this. You could leave the elements in an electric tank for dual fuel option if the tankless breaks down, or use electricity when it is “on sale” in evening hours.