Tankless Heater - hot water delay

[Rick Price]

I have a TWH locates in the garage. The laundry room is one the other side of the wall and hot water is almost instantaneous to the faucet. Master bath is about 20’ run and it takes 30-45 seconds to get hot water. Two bathrooms are on the other side of the house, approximately 60-70’ run. These faucets, shower and tub take 2-5 minutes to get hot water. These are only used when we have company. I have tried installing an on-demand recirculating pump at the furtherest point with cross-over to the cold water line. This only marginally improved the situation.

Looking for a better solution. Options I have considered are:
1. Install another TWH or WH near these rooms
2. Install a small WH near these rooms in series with the TWH. Operate this WH to keep hot water immediately available and feed hot water from TWH to the cold inlet. No recirculation. Ability to shut off WH when bathrooms are not in use.
3. Install continuous recirculation with ability to shut off when these bathrooms are not in use.

Appreciate guidance on best solution.

 

[Niccio]

Her's my quick stab at this: When you add a recirculation pump and crossover, it will only recirculate hot water to the faucet with the crossover creating a loop. Any faucets that tee off from the loop will not get hot water through their lines past the point where they tee off. The longer the lines to the faucet from the loop the longer the hot water will take to get to the faucet when you turn it on. This is likely why the pump had little effect. To remedy this, you can add a crossover to the sink faucet in the bathroom that you want to have hot water. This will allow the water to circulate to the sink faucet which will also bring it very close to the tub. Be aware though, that the more crossovers you use, the more your heater and pump will work. A good remedy for this is to connect your crossover with a quarter turn valve on one side. This way you can disable the crossover by closing the valve unless you're having company over, then you can crank it open a bit before they arrive and you'll have near instant hot water.