Contributor
Our situation was that the hot water heater was on one side of our house and our master bath was on the other side of the house. Took forever to get hot water.
I had the plumber split the system and we installed a gas tankless on the side of the house where the master bath is. It's not immediate hot water, but fairly quick.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
Member
That is why I installed the circulating pump have hot water in abou 3 seconds or less at the faucetsOriginally Posted by Mike Henderson
Contributor
But what do you do when your water heater is a tankless, as mine is? My original water heater is tankless and the second one I installed is also tankless. Seems that if the flow was sufficient to get the tankless to light up, it would be heating all the time. And if the flow was not enough to trigger the tankless to light up, you'd just get cold water.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
Member
You just add more tankless heaters before each faucet.
Moderator
Actually, at our old property, we had two units; one for the "original" portion of the house (kitchen, powder room and original master bath) and one for the large addition. (new master suite, new guest suite, laundry) The distance "over the river and through the woods" for the cold water connection between the two pieces of the home was sufficiently far enough that it was very undesirable to try and use a single water heater for everything.
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The most expensive tool is the one you buy "cheaply" and often...
Contributor
Mike, you understand the issue with tankless recirc perfectly. GPM x DeltaT X 500=BTU. Your tankless will have a minimum flow to initiate operation. I know Rinnai as I represented them for 30 yrs so will use their numbers. You can read the flow to .1 gpm on the touch pad. Generally min flow is .6 gpm to fire but it will hold operation down to .4 gpm. Minimum fire is 15 kbtu but again will hold fire down to about 10kbtu. So you must have a large enough Delta T and sufficient flow to initiate fire. To low a flow and to little DT and it will sit perfectly normally waiting for things to happen. Early after we introduced the tankless in ‘99 to the US market a customer wanted “instant” hot water so he put a honker circulator on it. I think it was a taco 0013 which is a hi-head pump and plugged it inot a socket. It killed the unit in 6 mos and Rinnai’s don’t give out in 6mos so we sent it back to the factory. Upon analysis it was found the unit had fired 88,000 times and had equivalent of 45 yrs of flow. Ridiculous. I have had success with the newer Rinnai’s with their wireless control with a wireless switch next to the kitchen sink up under the lower lip of the cabinet. Bathrooms have the wireless motion sensor so when you enter it makes the circ. The unit shuts down upon a warm return temp. That is on-demand recirc. In my last house I had this system and it had a the circ in the unit.
Contributor
That's an interesting idea about on demand recirculation. I'm going to look into that.
I really like my tankless water heaters. In southern California we can mount them on the side of the house, so I recovered the space where the tank water heater was - it's now a closet for things like vacuum cleaners, and accessable from inside the house.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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