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1K2GO 12-09-2007 07:43 AM

Noritz Tankless Install
Hi All,

I am installing a Noritz tankless WH in my new house that i am building. The instructions say to run the hot water supply in a "loop" from the heater to all of the faucets and then install a pump that pumps it back to the water heater. Is this really necessary, or can i just install in like a regular water heater would be installed. I guess i just dont understand the reasons behind this type of installation.


Kingfisher 12-09-2007 03:54 PM

The reason is to have hot water all ways right at the tap of every bathroom. I don't know that heater, but that is how I have all the homes I build plumbed with tank heaters:yes:

1K2GO 12-09-2007 06:22 PM


Originally Posted by Kingfisher (Post 79406)
The reason is to have hot water all ways right at the tap of every bathroom. I don't know that heater, but that is how I have all the homes I build plumbed with tank heaters:yes:

That doesn't make any sense because the water heater doesn't start to heat the water untill the faucet is turned on so there will be a wait period anyway. There has to be another reason for this setup, surly someone out there knows why?

jpplumber 12-09-2007 10:05 PM

I have installed about a dozen Noritz tankless water heaters and have not set it up yet like you have described. If you do put any type or recirc system the instructions are very specific on what they recommend on how to do it, auqastat (timer), pump and small holding tank. I don't recall that they recommend the recirc system, as it lowers the warranty on the heat exchanger from 10 years to 3 years (we were told this in the class we took at the Noritz showroom only 2 months ago), but that it is an option and to follow the schematic in the instructions.

1K2GO 12-10-2007 06:30 AM

So you would run it like a regular WH? Thanks

jpplumber 12-10-2007 07:42 AM

Yes, run it like a regular water heater but be sure to size the gas properly ( the biggest concern ) and to use the stainless steel venting that is required. (it will rust with galvanized pipe) The venting needs at least a 1 foot rise off the unit before a turn and you usually have to use a condensation tee on the venting. I think the only time the tee is not required is if the venting runs horizontally (with slight slope away from unit) to the outside after the 1 foot rise off the unit. The idea is to keep condensation from feeding back onto the unit. Hope this helps.

1K2GO 12-10-2007 08:03 AM

Ok, thanks, let me ask you this. I want to put it in the basement which is adjacent to the garage, above and completely back filled. Could i run the vent under the garage slab to the outside, if i were to sleeve it in a 6" pvc pipe? Otherwise i will have to move the heater up into the garage exterior wall. This is less than ideal because apparently you cant store anything like gas cans or the lawn mower in the same room because of vapors.


jpplumber 12-10-2007 08:57 AM

Ideally the venting length should be as short as possible and there is probably a max. length and number of bends allowed by Noritz. The venting is also expensive. The venting gets very hot and how would you propose to support the vent horizontally through this length under the garage. There are restrictions as to how close it can exit next to a window or door or clearance through drywall or wood. I can't see how the sleeve idea would be feasible and may actually be disallowed.

1K2GO 12-10-2007 09:41 AM

Do you think it will be an issue installing it in the garage with the fumes, if i keep the gas cans closed up tight? How gig of an issue is it? Is the flame not enclosed on the Noritz WH?

jpplumber 12-10-2007 10:12 AM

I think the requirements would be the same as for a tank in the garage, needs to be elevated at least 18" off the floor, as gas fumes are heavier than air. Even with this information I wouldn't be to comfortable with gas cans too near any source of flame. If the unit is enclosed in a sealed closet then you would have to have a (DV) direct vent unit that has an extra pvc vent that draws air from the outside. It would be a good idea to check with the local codes in your area to see if there are any special requirements beyond the recommendations of Noritz. The gas sizing seems to be the biggest concern for most municipalities because undersizing is a real problem. So the closer you are to the main gas coming into your home, the better. They may require a higher pressure gas meter and a separate regulator at the unit itself.

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