Tankless Water Heater Service in Heather Ridge Estates, Frisco, TX

Almost every conversion quote written in this neighborhood contains the phrase "upsize to 3/4 inch", and in a fair number of these houses that phrase is wrong. It is not wrong because 3/4 inch is a bad size. It is wrong because pipe capacity is not a property of diameter alone, and on the particular geometry these homes present, the run from a side-yard meter up to an attic platform is long enough that 3/4 inch stops being sufficient well before the pipe reaches the appliance.

Developed length

The full measured length of pipe from the meter to the appliance along the path the pipe actually takes, including every vertical rise and every horizontal detour, not the straight-line distance across the floor plan. On a two-story house with an attic appliance, the vertical component alone commonly adds twenty feet or more that a floor-plan measurement never sees.

Natural gas carries roughly 1,000 BTU per cubic foot, so a 199,000 BTU appliance asks for about 199 cubic feet per hour on its own, before the furnaces, range, dryer or anything else in the house is counted. The published capacity figures for Schedule 40 metallic pipe at a 0.5 inch water column pressure drop are the numbers that decide whether a given branch can supply that. They fall off faster than most people expect.

Read the second row again, because it is the one that matters here. At twenty developed feet a 3/4 inch branch is already below what a single 199,000 BTU appliance demands. A meter on a side elevation, a run along the exterior or through the garage, a rise up through a wall cavity and a horizontal leg across the attic to the platform is not a twenty foot run. It is frequently forty to sixty. On those geometries the correct branch is 1 inch, and the shortfall in a 3/4 inch installation does not announce itself on a mild day. It announces itself as flame loss under sustained draw on the first genuinely cold morning, which is exactly when the household notices.

Once the required diameter is settled, the cost sits almost entirely in the route. The original 1/2 inch branch was installed at framing stage, when every cavity in the house was open, by the shortest path that was convenient at the time. That path is now behind drywall, insulation and finished surfaces on two floors, and the new larger pipe has to reach the same place through a house somebody lives in.

That last row is the one worth asking about first, because it is the difference between a half day and two days. If a large enough riser already reaches the attic for some other reason, the new work is a horizontal extension across the attic and the job is straightforward. If it does not, somebody is opening a wall. A survey establishes which of those two situations you are in, and it takes about twenty minutes.

The reason to settle this before ordering equipment rather than after is that a route decision made on installation day is a route decision made under time pressure with the old appliance already disconnected. That is how a compromise gets built into a house for the next twenty years.

A wall-mounted condensing unit will physically hang almost anywhere there is framing to carry it. Whether it can be worked on afterward is a separate question, and it is the question that determines whether this appliance gets descaled every year for twenty years or gets descaled once, awkwardly, and then never again. In this housing stock the appliance is going back into the attic in most cases, so the attic has to be set up to be worked in.

• A solid decked platform in front of the unit large enough to stand and kneel on, not a plank laid across joists
• A continuous walkable route from the attic access to that platform, so tools and a descaling pump can be carried in without balancing
• Permanent lighting at the appliance with a switch at the access point, so nobody is working by flashlight over insulation
• A receptacle at the unit, both for the appliance and for the circulating pump a descaling requires
• Enough clearance in front of the unit that the front panel comes off without being wrestled around a truss
• Both isolation valve hose ports reachable with hoses attached and a bucket on the platform below them
• The vent joints and the condensate trap visible from that standing position, because a joint nobody can see is a joint nobody inspects

Capacity here is decided by the worst simultaneous minute the household actually produces, and in this housing stock that minute is usually a weekday morning rather than an evening. The governing equation is the same everywhere: gallons per minute equals BTU multiplied by efficiency, divided by rise multiplied by 500.

Frisco mains run about 50 to 55F in winter and a comfortable shower is about 105F, so the design rise is roughly 55F. Put a 199,000 BTU condensing unit through that equation at high efficiency and the paper answer is close to seven gallons per minute. We specify against 5.5 to 6.0 gallons per minute instead, because nameplate input assumes an ideal gas supply at sustained full fire and because a system sized with no margin becomes a complaint the first cold week the house is busy.

Now count the morning. Two showers is roughly 3 to 4 gallons per minute depending on the heads. A lavatory alongside them adds about another gallon. A hot laundry fill is intermittent but it can pull 1.5 to 3 gallons per minute while it is filling, and it lands squarely inside the same window because nobody schedules laundry around showers. Add those and you are at 6 to 8 gallons per minute, which sits at or past the top of a single unit at winter rise. That is why the answer in these plans is a 199,000 BTU unit rather than a mid-output one, and why the laundry timing is worth a sentence of conversation rather than being ignored.

This is permitted, inspected work performed by a licensed plumber, and on an attic conversion the inspector's list is fairly predictable. Knowing it in advance is useful mostly because every item on it is something a low bid can quietly omit.

• Gas branch sized for total connected load at the actual developed length, and pressure tested
• Vent material matching the appliance category, with the manufacturer's maximum equivalent length respected
• Termination clearances held to windows, doors, soffit intakes, grade and the property line
• Condensate routed to an approved receptor through a neutralizer, with continuous fall and no sag
• Freeze protection powered from a dedicated unswitched circuit that cannot be turned off by accident
• Relief valve discharge piped correctly and terminating where a discharge would be noticed
• Appliance accessible for service without dismantling anything else

Frisco Tankless Water Heater Pros works out of 6960 Parkwood Blvd in Frisco 75034, which is close enough to reach this neighborhood for a survey before quoting rather than pricing from a template. On an attic job the survey is worth more than usual, because the two most expensive variables, the gas route and the platform access, are both invisible from the driveway. Call (972) 430-9024 and we will look at the actual run before anyone quotes a number.