Undersink instant hot water heater question

[todenbach]

I have a 2.5 gallon Bosch heater that I wanted for instant hot water instead of waiting for my on demand unit. I intended to supply the unit from the cold water supply so that the on demand unit will not come on every time someone washes their hands. It seems like when I turn on both faucets the pressure on the inlet is bound to drop resulting in no hot water pressure. I would really appreciate any suggestions.

 

[phishfood]

I am having trouble understanding how you have the heater plumbed in. Can you post a picture of this?

 

[todenbach]

I split the cold water just past the shut off valve and ran one leg to the heater cold water intake and the other leg to the cold water faucet. I ran the hot water out of the heater to the hot water faucet. The hot water shut off valve at the wall is shut off and not being used. I hope that clears it up. I could really use all good advice available. Thanks, Terry

 

[havasu]

It sounds feasible to me, until you run out of hot water in the small tank.

 

[phishfood]

It sounds as though a restriction somewhere on the hot side is allowing water flow to prefer the cold side. Either a line is kinked, there is dedebris in the cartridge, the water heater has a restrictor built into it, something of that nature.

The most likely thing to fix it would be to attach the water heater to the supply pipe BEFORE the supply valve. That pipe will be much larger than the supply tube that you are currently attached to, providing sufficient volume and thereby pressure to both the hot and the cold side.

 

[todenbach]

That sounds like an excellent idea and easy to implement. Thanks for the good advice. I appreciate your time to respond.

Terry

 

[plumbingjim17]

agree Re-pipe but also there is a inlet screen on these things that can plug up so if it hasn't always been like this I would check this.

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