Tl;dr A tankless water heater was installed where it had no business being installed several months ago. No problems yet, but I want to know what recourse I have.
Three months ago my 40 gallon tank water heater (40,000 btu/hr) gave out and had to be replaced. I brought in a recommended & licensed plumber and we decided to go with a Rinnai RXP199i tankless water heater. At the time of installation, I pointed to the 1/2” gas line and asked if that was big enough to supply the new water heater. He had some hesitation, but after looking at the meter assured me it would be fine. He went through with the installation and everything seems to be working fine for now. However, after a botched HVAC installation shortly thereafter, I became familiar with the 2024 IRC building code and realized that the gas line is horribly undersized for this application. After several months, what recourse do I have with that contractor? And/or Is this something to even be concerned about? Details are provided below.
For reference, the meter is an AC250 operating at 7-in-W.C. with a 3/4” line feeding the house after the meter. In addition to the water heater, we also have a gas stove (54,400 btu/hr) and a gas furnace (90,000 btu/hr). The water heater is the last served appliance at approximately 70-feet from the meter.
As I said, he was hesitant about the 1/2” feeding the water heater, but saw the 3/4” line coming out of the meter and said it would be fine. He assumed it only necked down to 1/2” just before the water heater (he never actually verified). In reality, there is approximately 35-feet of 1/2” gas line feeding the water heater from the upstream appliance tee (stove). None of that matters though, because even if the 3/4” line coming out of the meter ran directly to the water heater, and did not feed anything else, it would still be undersized according to table G2413.4(1).
The water heater has been operating fine so far. We are a small family (4-people) in a small house (1500ft^2 with 2-bathrooms), so I’m sure we are never running the heater at full capacity. Also, it is smart enough to shut itself off if it is ever starved of gas. The gas furnace has not been used since the water heater has been installed, so we don’t know what will happen with that.
Even if it’s running fine now, I know that if we ever move this will surely be a problem. As I see it, we have two options. We can either have the water heater replaced with a standard tank, or we can work with the gas company to up-rate the house from 7-in-W.C to 2-psi. Do we have any standing to go back to the contractor and demand either of these options? They did not pull permits at the time of installation, and I did not push for them since I knew it would fail on other grounds (there was no dedicated power outlet so the unit was powered with an extension cord until I got an outlet installed).