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natemclain 06-05-2009 11:58 AM

Bosch 1600H Tankless Water Heater
1 Attachment(s)

I have been lurking around for awhile. Just thought I would see if anyone had any information to help me out.
I just installed a bosch 1600H tankless water heater for a 800 sq foot addition to my house. This is mainly a master bedroom, walkin closet, & 1/2 bath for the addition.
I have no experience with tankless water heaters but I don't know if I like them yet.. ;-)
No to the problem.
To get enough flow to keep the water heater running my wife has to mix to much cold water with the hot therefore reducing the hot water flow below the 0.6 GPM rating for minimum flow for activation. So I thought, I will adjust the water temp so that it suits her needs and I can always use less cold water for a warmer bathing experience... Well when I do that the sink faucets don't activate the hot water while washing your hands. You might as well never turn the hot water on. So that is annoying. I have adjusted to try and find a happy medium but there doesn't seem to be one... And I'm trying to make my wife happy (which isn't hard to do, just provide the right temp water when she wants it... ;-).
Here is a run down of the install info.
3/4" NG line, roughly 35' long coming from a 1 1/4" main gas line.
This heater is the only appliance on this gas line. I have a 5" vent pipe with no bends in it, straight up and out of the room through the ceiling and roof.

Do I just have the wrong size tankless water heater for my application? Or is this what the Europeans have dealt with all these years.. ;-)
Not a huge deal, its just not what this American has been use too. There are pros/cons from what I have seen from the traditional tank & tankless water heaters. I love the fact that I can take an hour long shower with my wife. (When the water temp is right... LOL).

Here is a picture of my install. (I know the pressure relief valve wasn't installed in this pic for all you over observant types... ;-)

Any input would be great.


Clutchcargo 06-05-2009 12:34 PM

63 Attachment(s)
Are you saying that with the sink hot faucet fully on, you don't get enough flow (0.6 GPM) so that the water heater turns on?

natemclain 06-05-2009 01:00 PM

Well in the 1/2 bath if you turn the water on full it activates, but in the master bath we have some faucets and they must be some low flow faucets because if you try to adjust the water flow at the water heater they won't activate. But the 1/2 bath faucet always kicks on the heater.

Ron6519 06-05-2009 02:19 PM

It looks like you have two gas shutoff's on the water pipes and a water shutoff on the gas pipe.
Doubtful any of the installation is correct.
Call in a plumber before you blow the little lady up.

jsmith929 06-05-2009 05:24 PM

This seems to be the problem with the newer tankless,my brothers older Bosch works perfect with the newer low flow faucets.Now my dads brand new Bosch 2400 the flow valve does not turn on fast enough for him and I suggested a small 6 galon 120 volt water heater to be used as a bump tank ( if thats the right wording).I believe Bosch actually recommends this method in their instructions.

natemclain 06-05-2009 11:04 PM

Ron - You are correct about the gas shutoff valves. I had the one valve already and the paperwork on the valve said it was acceptable for NG so I used it.
All the valves indicated they would work for what they re being used for.
I had a HVAC guy stop by to look at the install and he didn't find anything wrong with the install. I guess I should have made a note in the OP about the gas valves like I did about the PRV not being in the installation at the time the picture was taken. :wink:

beenthere 06-06-2009 07:48 AM

You bought the wrong size unit.

Bigfoot 06-06-2009 08:07 AM

I usually troubleshoot from simple to complex. The first thing I'd do is unscrew the screens from the faucets, see how much junk is trapped in there and then give it a try without the screens. Mixing valves can be problematic for the same reason the screens fill up with junk. Purging the lines is always a good idea after any new installation.
The only similar trouble I've seen with similar units, is without a recirculation line plumbed in, it can take a while to purge the cool water from the hot water lines on long runs.
I'll ask my son whenever he gets his lazy rear out of bed and have him post up, he has worked with these systems a lot.

Talked to my son and he said, you can't put a recirculation line on these systems (though I have seen recirculation taps on similar units). He mentioned the supply pressure may be low and asked if you have a pressure regulator in the water supply line or well water and a pump? He also said to turn the temperature down to make the unit more responsive, which I don't fully understand, but seemed logical to him. He also said the flow meter/switch on similar units is adjustable, he isn't sure about the Bosch unit. He also said the vacuum lines (his words) to the flow switch are small and can get plugged, the "O" rings in the flow switch are a known trouble spot.

Talked to another plumber, he said the burner may be having trouble starting, most likely a partially plugged jet. Something left in the water supply lines, like a plastic cap or other trash in the water lines.

That's the main problem with the hot water on demand systems, they are just too complex, too many things to go wrong. The main reason I've held off installing one until my 30 year old water heater dies.

beenthere 06-06-2009 05:38 PM

On that Bosch unit.
It you turn the temp down, its less responsive, it can take a 1.1 GPM flow to start the ignitor.
At highest temp it only takes a .5GPM to start it.

vsheetz 06-06-2009 11:16 PM

I have a Bosch tankless water heater. Our kitchen fauset would not always bring on the heater (if not, turning it off and on a couple times would bring on the heater), where all other taps in the house would work just fine. I never worried about it, as the kitchen was slated for a remodel. The kitchen has now been remodeled and the fauset replaced - no more issue, the problem went away with the old fauset...

So, as others have suggested, check out the fauset.

Oh, we love the water heater - endless supply of hot water for the soaking tub or shower. And power savings of not having to continueally heat a tank of water for occational usage.

dotmatrix 08-09-2009 12:15 PM

Tankless water heater Navien cr-210
I am looking at installing a tankless waterheater.
I have been looking at the Navien CR-210.
Does anyone have any positive or negative feedback about this system?
I know that they are more expensive than others on the market, but on paper they appear to be more efficient 98%.
I have read some very negative reports about the CR-240.

I am looking at this system for various reasons.
Is this system:
reliable, cost effective, or loud?

OffRoadAudio 08-24-2009 10:09 AM

I have a Rinnai tankless and simply set the temp to 115 and use full hot - no cold, works great.

Michael Thomas 08-24-2009 10:32 AM


The required pressure relief valve (supplied with the water heater), pp 13


has not been installed.

Michael Thomas 08-24-2009 10:33 AM

Deleted duplicate post

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