Apollo HydroHeat Combo Replacement in Novato: A Real Job

Some Novato homes don't have a separate furnace and water heater. They have one gas water heater doing both jobs: making hot water for the showers and sending hot water to a fan coil that heats the house. Last month we replaced one of these Apollo HydroHeat combo systems' water heaters in Novato. Here's what we found, what we installed, and what to know if your home has one. Questions about your own system? Call or text Local Plumbing at (415) 234-0370.

The Home and the Problem

This Novato home's hot water and heat both came from an Apollo HydroHeat combo system. In a combo like this, a gas water heater in the garage heats the water. Some of it goes to the faucets and showers. When the thermostat calls for heat, a pump sends hot water from the same tank to a hydronic coil in an air handler, and a blower pushes warm air through the ducts.

It's a clever, compact setup, and when it works, homeowners barely think about it. But it puts a lot of load on one appliance. The water heater cycles for showers, dishes and laundry, and also for every hour the heat runs in winter. In this home, the water heater at the center of the system needed replacing, and getting it done in September meant the home went into heating season with a new heater instead of an old one.

What We Looked At

Replacing the water heater in a combo system isn't the same as a standard swap. Before quoting, we looked at:

• Capacity and recovery. The new heater has to keep up with both the household's hot water use and the heating coil. An undersized heater means lukewarm showers when the heat is running, or weak heat when someone's in the shower.
• Venting. Could the new heater use the existing flue safely, or did the vent need to change?
• Gas supply and valves. Shutoff valves and connections were original, and it made sense to replace them while the heater was out.
• Where a leak would go. The heater sits in the garage. A drain pan with a drain line protects the space if the tank ever leaks.
• The heating loop. The pump, piping and air handler that make up the space-heating side stayed as they were. Our job was the heart of the system, the water heater, and reconnecting it properly.

What We Installed and Why

Bradford White URG250H6N

We installed a Bradford White URG250H6N: a 48-gallon, tall, 55,000 BTU natural gas water heater with an ultra-low NOx burner and atmospheric venting. A standard 40- or 50-gallon home water heater is typically in the 36,000–40,000 BTU range. This model's higher input means faster recovery, which is exactly what a combo system needs when the heat and the hot water are drawing from the same tank at the same time.

Because it's atmospherically vented, it connected to the existing flue without a new vent run, which kept the job simpler and the cost down.

The rest of the job

• Removal and disposal of the old combo water heater
• New water and gas shutoff valves
• A drain pan with a drain line to the garage floor
• Reconnection of the water piping, including the connections to the heating loop
• Securing and checking the flue connection
• Testing and commissioning for safe operation, on both the hot water and heating sides
• A city permit, with our technician meeting the inspector on site to complete the inspection

The Result

The home has a new, high-recovery water heater feeding both its hot water and its heat, with new valves, leak protection and a passed inspection. It's backed by Local Plumbing's one-year labor warranty plus Bradford White's manufacturer warranty.

Combo Heating Systems in Novato: What to Know

Combo systems like Apollo HydroHeat were installed in many Bay Area homes in the 1980s and '90s. If you live in a Novato neighborhood like San Marin, Indian Valley, Pointe Marin or Ignacio and your furnace closet has an air handler with water pipes running to it instead of a gas burner, you may have one. A few things to keep in mind:

• Your water heater is part of your heating system. If it fails in January, you lose heat and hot water at the same time. Don't let it run to failure.
• Size the replacement for both jobs. A standard low-input heater may not keep up. Ask whoever quotes it how they sized it.
• Keep the heating loop healthy. Have the pump and the coil checked, and make sure the loop is set up so water doesn't sit stagnant in the coil all summer.
• Flush the tank. Every tank collects sediment over time, and a combo heater cycles more than most. Regular flushing helps it last.
• The 2027 Bay Area rule. Under the Bay Area Air District's current rule, gas storage water heaters up to 75,000 BTU/hr made after January 1, 2027 must be zero-NOx (a proposed amendment could push this to 2028). It applies to new units sold and installed, not to working equipment, so nobody has to remove a heater that's working. If your combo heater is getting old, replacing it before the rule takes effect keeps more options open. See our 2027 gas water heater rule page.

Apollo HydroHeat and Combo System FAQs

Can a combo system's water heater be replaced with a tankless heater?

Sometimes, but it needs careful design. Tankless heaters need a minimum flow to fire, and the heating loop has to be piped correctly to work with one. In many combo homes, a high-input tank is the simpler, more reliable choice.

Do I have to replace the air handler too?

Not necessarily. If the air handler, coil and pump are in good shape, we replace only the water heater. If they're aging too, we'll tell you and give you options.

Does replacing a water heater in Novato need a permit?

Yes. Water heater replacements need a permit and inspection. We pull the permit and meet the inspector, so you don't have to.

How long does it take?

A direct replacement like this one is usually done in a day, followed by the inspection.

Water Heater and Combo System Replacement in Novato

Local Plumbing serves Novato and all of Marin and Sonoma counties, from Hamilton and Bel Marin Keys to Black Point and Marinwood. Our warehouse and training facility is in San Rafael, minutes down 101. We're a licensed C-16 and C-36 contractor (Lic #1091739) with 340+ five-star Google reviews. See our Novato plumbing page and our Bradford White water heater page.

Have a combo system or an aging water heater? Call or text (415) 234-0370, or contact us, for a free replacement estimate.