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Robert Lamoureux: Low NOx means less hot water

Posted: May 8, 2009 9:54 p.m.
Updated: May 8, 2009 4:55 a.m.
Hi Robert,
I hope you can help answer some questions I have about water heaters. My water heater sprung a leak about a month ago, so we had it replaced. The plumbing company put in a new Bradford White unit model # U45036FRN Ultra Low Nox series 50-gallon 40,000 BTU's.
I had a unit before - also a 50-gallon. The problem I have with this new unit is after two people in our house take their showers there is no more hot water for the next three people. Everyone at our house takes about a 15-minute shower.
When my old unit was working we could all take showers and still had some hot water left. I called the plumbers who installed the unit and they came out and said the problem is that the new codes for my city requires them to put in ultra low NOx systems, and we will always have this problem. Any ideas what we can do would greatly be appreciated. Thank you,

David R.

Hi David,
What you've got is one of the new environmentally friendly, green water heaters with low NOx, nitrogen oxide, that meet emission standards of California's SCAQMD - South Coast Air Quality Management District. Lowering NOx emissions reduces smog, acid rain and ozone depletion.
One of the ways they reduce the formation of NOx is to reduce the flame temperature that heats the water. Since the temperature has been lowered, it drops the recovery time of available hot water. So, although you have the same size tank as before, you have to wait longer for the water to heat. Usually, with low to no hot water problems, we look at several things including mineral deposits, the thermostat, elements, the limit switch, etc. In your case, using a new low NOx system looks to be the culprit. If everything else is working correctly the only way to resolve this problem would be to add capacity. You could put in a larger commercial/residential grade tank, or add a secondary tank if you have the room.

Mr. Lamoureux,
Our property manager told me about your column and I've been a fan ever since. Basically, we had a planter on top of our parking garage that was leaking onto the cars below. We had it excavated and waterproofed. The inspector then said we had to install two planter drains. Our contractor said this additional work, because the slab is 18" will cost close to $4,000 which sounds very high to us and we feel unnecessary anyway since the planter is now waterproofed. Thank you,
Jerri D.

Hi Jerri,
I'm not sure what you're asking. Is $4,000 a fair price, or do you need to abide by the wishes of the inspector? I would say, very possible and absolutely.
Regarding the inspector - he represents the Department of Building and Safety and they have the final say. What he says is law, period. Let's say you disagree and have the contractor backfill the planter without the drain. You could not only get fined, but it is possible he could order the work to be done by another contractor and then back charge your account. Either way, it will cost you less to follow his instructions from the start.
As far as the $4,000 is concerned, an 18" podium slab is full of rebar and post tension - PT cables. To install a drain, you will need to core through this slab. Before coring, it will have to be x-rayed to find a spot that is safe to core through. You are charged per shot, meaning if the first area is found unsafe to core, they move on to another location and x-ray there for an additional fee, and so on.
On a slab that thick, the x-ray lab will need to use cobalt. The contractor would also need to coordinate with all residents of your complex and surrounding buildings that are within 75 feet of the x-ray site. Tenants and pets need to be evacuated. Since there is no way of knowing how long it will take, we usually arrange for all tenants to be out from 8 a.m. to noon.
After a safe core site is determined, the concrete has to be cored and then cast iron pipe is mounted to the parking garage ceiling underneath to discharge. The costs of x-rays, coring, pipe, plus the time and expense of permits and acquisitions and meeting with the inspector could easily reach $4,000 for this project.

Mr. Lamoureux,
We just bought a house and have already discovered some sewage problems directly under the slab of the garage. I want to dig it up and replace about 40' of line out to the main, but what's the best way to get under the garage which is 20' long? Thank you,
Ken K.

Hi Ken,
First of all, how deep is your sewer line? At my house it's 17 feet deep. With 40 feet of excavation and shoring, you're talking about a huge job. I would start by calling a plumber with a camera to determine what the problem is exactly and just replace what is necessary. While there, have them give you a proposal to saw cut through your garage slab to make the repair if that's all that is needed. If you do need to replace 40 feet of pipe that travels under your garage, I would leave the slab alone. Come back far enough from the garage that would allow you to put in some sweeps and go around the side of the garage, not under it.
Also, if a 40-foot replacement is necessary, a plumber will not be able to help you when you get to the city main. Only a sewage contractor is legally allowed to saddle into the main city sewage line.

Hello Robert,
This is the first time I have written to any newspaper column. I am putting in an above ground spa in my backyard and would like to know how I should get the 220 electric out to it. Thank you,
John L.

Hi John,
With any electrical questions, I always want to put in the disclaimer that the work should be done by a qualified electrical contractor. For your jacuzzi, you will need a dedicated 220volt 50 amp GFI protected service. Have the electrician bring out two #6 hots and a ground. The electrician will bring power off a double pole breaker in the panel. Run one-inch metal conduit down from the panel to two feet underground. Once you're underground, you can transition to PVC to save on the materials. The one-inch pipe will not only make your pull easier, but it will give you room to add another circuit out to the spa.
While you're at it, spend a little more time and pull an extra circuit or two and hook up a service outlet. Having been there a thousand times, you never know what you may want in the future. This way, if you want to plug in your weed-whacker, or install a plasma screen above the spa, you'll already have the power there.

Robert Lamoureux has 25 years experience as a general contractor, with separate licenses in electrical and plumbing contacting. He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor, after that contractor has made a thorough visual inspection. Send questions to


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