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Rinnai Tankless Installation Issues


dtontarski
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I've yet to see a single on-demand water heater installed per the manufacturer's instructions.

I generally write up the most obvious installation deficiencies, provide an embedded link to the manufacturer's installation manual, recommend corrections be made by a qualified professional, and when possible, provide side-by-side photos of the deficiency versus how things should have been done.

I like to include the side-by-side photos, as I've come to realize that the majority of my clients don't take the time to read my full reports or follow links - the photos suffice for these folks.

Does anyone have any photos they would be willing to share of the proper exterior vent termination of a Rinnai Model R75LSi?

The manufacturer's manuals contain diagrams that are not very clear to anyone other than the installer that has all of the tangible parts right in their hands.

The exterior install on this one was very shoddy, and finishing components are missing. (and yes - I realize this unit must be relocated, as it is less than 12" from an inside corner)

One more request - the installation manual calls for 3/4" hot and cold water supply lines - the individual that installed this unit had 3/4" PEX connected to the valves at the base of the unit, but both lines were immediately (within several inches) reduced to 1/2" PEX).

(Yes - The missing PRV extension pipe was called out)

Plumbing is not my strong suit, but it would seem logical to me that the cold water supply line would have to be 3/4" right from the source (the interior meter in this case), and I'm not clear on the specifics of at what point the hot water supply line can be reduced, but within a few inches seems to defeat the purpose of this manufacturer's requirement.

A better understanding of this is what I am looking for.

Thanks.

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Most all tankless systems require a 3/4" gas supply line and that means a full 3/4" back to the main distribution leg that may be 1-1/2" or 2", etc..

Any reduction (via elbow or whatever) to 1/2" and then back to 3/4" is not acceptable, from what I've learned over the years.

Any reduction will not allow the unit to operate at design specifications and the clients likely won't be too happy with their 'spensive installation.

I had one client who had her tankless unit installed 3-times (took the 3rd plumber to actually read the installation instructions and follow them).

Once he fixed a few other things and made sure the gas supply was the specified size throughout ... it all worked as it was supposed to.

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. . . One more request - the installation manual calls for 3/4" hot and cold water supply lines - the individual that installed this unit had 3/4" PEX connected to the valves at the base of the unit, but both lines were immediately (within several inches) reduced to 1/2" PEX).

(Yes - The missing PRV extension pipe was called out)

Plumbing is not my strong suit, but it would seem logical to me that the cold water supply line would have to be 3/4" right from the source (the interior meter in this case), and I'm not clear on the specifics of at what point the hot water supply line can be reduced, but within a few inches seems to defeat the purpose of this manufacturer's requirement.

A better understanding of this is what I am looking for. . . .

For this particular issue you might want to look to the plumbing code instead of the water heater's installation instructions. In the IRC, that would be in section 2903. The correct size of any individual distribution pipe will depend on the water pressure, the meter/service pipe size, and the number of fixture units that it supplies.

- Jim Katen, Oregon

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Sounds like I should just cite the specific issues that do not comply with the manufacturer's installation instructions (that I am certain about), recommend that the installation be further evaluated, and that all installation deficiencies be corrected by a qualified professional.

Short of going way beyond the scope of my job and calculating "the water pressure, the meter/service pipe size, and the number of fixture units that it supplies", is it safe (accurate) to say that there is an issue with the water supply line reductions?

Still looking for opinions (not necessarily code cites) on whether it is wrong to make these reductions, when the instruction manual clearly states that 3/4" hot and cold supply lines are required.

I have never seen water supply line reductions right beneath a unit like this.

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Will the appliance produce hot water as it is installed?

Yes, up to the limitations of the PEX. Its about the rate of flow the pipe can carry. The water heater does not how large the pipe is, only how much water is flowing to it. As Jim stated the pipe size is a design issue.

Do you call out the PEX connected directly to the WH?

I do agree with citing what you see/know/find and recommending a plumber install the appliance in full compliance with the manufacturer's installation instructions.

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I would take into account the number of fixtures served and how far they are from the heater. If that heater only serves a kitchen and a bath, 1/2" might be enough. And, the plumber may know that with the time it takes for the heater to get to full fire PLUS the time it takes for the hot line to flush, the 1/2" will result in a more satisfied customer.

Of course, if that unit serves a kitchen, three baths, a laundry room, and whatever else, the 1/2" is ridiculously inadequate. Maybe the installer was nearly out of 3/4" PEX that day.

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Charlie -

I did not call out the PEX being directly connected to the water heater. Based on this previous post, this seemed to be more of an overheating of the PEX near a vent issue:

https://www.inspectorsjournal.com/forum ... IC_ID=9171

I'm going to give Rinnai a call next week regarding this install and follow up to this post with any helpful information I receive.

Thanks -

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David -

I believe that you nailed it with "ridiculously inadequate". This unit serves every plumbing fixture in a new nearly 3,000 square foot home with 3 baths. I've been googling this for hours, and though I never found the specific information I was looking for, I am now convinced that this requires further evaluation, and likely some re-plumbing.

Thanks.

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From what I gather reading this site, some home inspectors verify/evaluate hot water flow at the fixtures. I would start two hot showers, hot at the kitchen sink, and see what you have. It will probably be marginal. Start filling the washing machine and it will probably be completely unacceptable. If the plumber ran 1/2" lines thru the whole house, he has caused a huge problem--a sensible plumber is going to plan and install one or more 3/4" (or larger) lines from the heater that branch off and feed the house in a way such that enough hot water flow can be had at all of the fixtures even when there are several running. The exception would be a home run system, where small lines go to each room, but in that case a manifold would be fed by a 3/4" or larger line. That house probably has a very significant plumbing issue, regardless of the type of heater installed. Even a large tank wouldn't be able to send enough BTUs thru 1/2" lines to keep everyone happy.

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I had a Rinnai installed in October and told the plumber that I was a home inspector and had the install instructions from their website. I think this caused my plumber and his tech to take some extra time to do it right. So much so, that they forgot and left a roll of 1" CSST in my basement when they left.

My installation is a bit better than the one in the OP. The vent comes through my concrete block wall with a piece of PVC pipe flashing to create a water-tight seal at the vent. They used copper for about 18" out of the unit and then connected it to PEX (my house is plumbed with PEX). I confirmed the 12"clearance above grade for the exterior vent.

I can't believe that a qualified reputable contractor would leave the vent pipe penetration looking like it does in the 1st photo. Low quality install, if you ask me.

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I had a Rinnai installed in October and told the plumber that I was a home inspector and had the install instructions from their website. I think this caused my plumber and his tech to take some extra time to do it right. So much so, that they forgot and left a roll of 1" CSST in my basement when they left.

My installation is a bit better than the one in the OP. The vent comes through my concrete block wall with a piece of PVC pipe flashing to create a water-tight seal at the vent. They used copper for about 18" out of the unit and then connected it to PEX (my house is plumbed with PEX). I confirmed the 12"clearance above grade for the exterior vent.

Good for you. I keep trying to figure how to market a concept in which every homeowner has a home inspector on his speed dial for when issues or the need for a repair is needed. The homeowner situates his 'representative' between him and the contractor to reduce the chance of sub standard or hazardous workmanship.

Marc

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I keep looking at Jeremy's avatar.

Unless my reasoning is seriously flawed, nothing is going to happen to anyone sticking a scissors into a receptacle the way that one has been stuck in there. Now, do it corner to corner or both on that right side where the hot slots are and I bet there'll be a really loud pop, a shower of sparks, the tips of those scissors will be melted away and someone will have to clean out his shorts.

ONE TEAM - ONE FIGHT!!!

Mike

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Charlie -

I did not call out the PEX being directly connected to the water heater. Based on this previous post, this seemed to be more of an overheating of the PEX near a vent issue:

https://www.inspectorsjournal.com/forum ... IC_ID=9171

I'm going to give Rinnai a call next week regarding this install and follow up to this post with any helpful information I receive.

Thanks -

No prob but I disagree. Its a manufacturer's installation instruction issue. Smarter people than us engineer the products we inspect. I retain as many installation manuals as I can for the products I inspect.

Just sayin

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Charlie -

I discussed the PEX connection to the water heater with a Rinnai representative today. He confirmed that there is no Rinnai documentation that prohibits this.

I also confirmed what earlier posts have discussed - PEX can generally be connected directly to both electric and gas water heaters, providing that the PEX is kept at least 6" away from the exhaust vent of the gas units, and providing there is nothing in the water heater manufacturer's installation manual, or in the locally enforced codes, that specifically prohibits a direct connection.

Plus - the Rinnai rep said that there is no Rinnai documentation that would prohibit the immediate reduction from 3/4" to 1/2" on the water supply lines, but he agreed, as other posters, that this was not a standard method by which to plumb this, and was surprised that this was completed this way in new home with as many plumbing fixtures as this one had.

An archived post on a plumber's forum suggested the following demonstration be done for the homeowner (who was not present during my inspection) - he said to turn on the hot water first at the kitchen faucet, then in both upstairs showers, and to then start the washing machine (on a hot wash setting). The poster said this would most likely clearly demonstrate the inadequacies of this type of set-up.

Plus - We discussed that PEX should not be used as a PRV extension pipe material.

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I've always been told by plumbers that 1/2" pipes could service no more than three plumbing fixtures and, in my own mind, assumed it was based on a code. A quick search of my own State's plumbing code, though, didn't uncover any such requirement.

It seems ludicrous that a plumbing code wouldn't address supply-pipe sizing, but maybe this is one more instance in which I'm . . . wrong (Ugh, the pain associated with saying that).

Does anyone know if plumbing codes specifically address the issue?

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I've always been told by plumbers that 1/2" pipes could service no more than three plumbing fixtures and, in my own mind, assumed it was based on a code. A quick search of my own State's plumbing code, though, didn't uncover any such requirement.

It seems ludicrous that a plumbing code wouldn't address supply-pipe sizing, but maybe this is one more instance in which I'm . . . wrong (Ugh, the pain associated with saying that).

Does anyone know if plumbing codes specifically address the issue?

Of course they do. It's one of the most basic parts of the plumbing code. However, it's not as simple as "three fixtures per 1/2" pipe."

Go to section 2903 of the IRC. You will, find a simple chart that shows how many fixture units you can run off of a given pipe depending on your water pressure and your meter/main pipe size.

Distribution pipe sizing has nothing to do with the water heater or the water heater manufacturer.

- Jim Katen, Oregon

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I've always been told by plumbers that 1/2" pipes could service no more than three plumbing fixtures and, in my own mind, assumed it was based on a code. A quick search of my own State's plumbing code, though, didn't uncover any such requirement.

It seems ludicrous that a plumbing code wouldn't address supply-pipe sizing, but maybe this is one more instance in which I'm . . . wrong (Ugh, the pain associated with saying that).

Does anyone know if plumbing codes specifically address the issue?

Of course they do. It's one of the most basic parts of the plumbing code. However, it's not as simple as "three fixtures per 1/2" pipe."

Go to section 2903 of the IRC. You will, find a simple chart that shows how many fixture units you can run off of a given pipe depending on your water pressure and your meter/main pipe size.

Distribution pipe sizing has nothing to do with the water heater or the water heater manufacturer.

- Jim Katen, Oregon

I think John may have been referring to the pipe supplying the water heater, but then, maybe not.

Marc

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I've always been told by plumbers that 1/2" pipes could service no more than three plumbing fixtures and, in my own mind, assumed it was based on a code. A quick search of my own State's plumbing code, though, didn't uncover any such requirement.

It seems ludicrous that a plumbing code wouldn't address supply-pipe sizing, but maybe this is one more instance in which I'm . . . wrong (Ugh, the pain associated with saying that).

Does anyone know if plumbing codes specifically address the issue?

Of course they do. It's one of the most basic parts of the plumbing code. However, it's not as simple as "three fixtures per 1/2" pipe."

Go to section 2903 of the IRC. You will, find a simple chart that shows how many fixture units you can run off of a given pipe depending on your water pressure and your meter/main pipe size.

Distribution pipe sizing has nothing to do with the water heater or the water heater manufacturer.

- Jim Katen, Oregon

I WILL kiss your ass on Main Street and give you an hour to draw a crowd if any plumber in my area has looked at that chart--or a similar iteration thereof--since he attended technical school.

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I've always been told by plumbers that 1/2" pipes could service no more than three plumbing fixtures and, in my own mind, assumed it was based on a code. A quick search of my own State's plumbing code, though, didn't uncover any such requirement.

It seems ludicrous that a plumbing code wouldn't address supply-pipe sizing, but maybe this is one more instance in which I'm . . . wrong (Ugh, the pain associated with saying that).

Does anyone know if plumbing codes specifically address the issue?

Of course they do. It's one of the most basic parts of the plumbing code. However, it's not as simple as "three fixtures per 1/2" pipe."

Go to section 2903 of the IRC. You will, find a simple chart that shows how many fixture units you can run off of a given pipe depending on your water pressure and your meter/main pipe size.

Distribution pipe sizing has nothing to do with the water heater or the water heater manufacturer.

- Jim Katen, Oregon

I think John may have been referring to the pipe supplying the water heater, but then, maybe not.

Marc

No, Marc. That's been the general rule where I am regarding ALL supply piping.

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. . . I WILL kiss your ass on Main Street and give you an hour to draw a crowd if any plumber in my area has looked at that chart--or a similar iteration thereof--since he attended technical school.

No need for threats.

You might be right about the independent plumbers who do residential work. Those guys pretty much just do whatever they can get away with. But I'll bet that the union guys and the commercial plumbing contractors in your area are very familiar with that chart. In fact, the more experienced ones probably have portions of it memorized.

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Something to remember when you run into a home that has replaced their old gas water heater with a new tankless model. There could be an issue with the amount of gas delivered to the home.

Tank water heaters use an average of 36k btu on a standard 50 gallon model up to 88k btu on a standard 100 gallon model. They are supplied with a 1/2" gas line to the valve. Not a problem.

Now the owner comes in and replaces this with a tankless gas water heater. These units operate at 199k btu, quite a bit higher, and needs to be supplied by a 3/4" gas line.

There are numerous things you need to check when this change is done. Gas is delivered to a normal home through a meter that normally supplies 250 cfh, or 250k btu. The meter must deliver enough gas to supply all appliances operating at the same time. So let's take a look at an all gas house.

New tankless water heater = 199,000 btu

Standard Furnace = 48,000 btu and up

Oven / Stove = 48,000 btu

Fireplace = 39,000 btu

Total 334,000 btu.

By exchanging the old tank style water heater with the new tankless, you have exceeded the standard gas meter output and also the capacity of the initial 3/4" gas line into the home.

The only way to take care of this issue is to upgrade the gas meter to a higher capacity model that can also operate at a higher pressure. But that means a pressure reducer is needed at each appliance. These are not inexpensive upgrades from the gas company. They can be pretty spendy.

So if you see a tankless water heater, start by checking the capacity of the gas meter and how many appliances use gas. This could be an issue for your client.

There is also the issue of the b-vent, which could be undersized for the additional btu output, especially if it is combined with the furnace.

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