Example Geothermal Heating Projects in Everett

Scope of work

A heat loss calculation, the loop design, two vertical bores with grouted loop pipe, the pipe trenched to the house, the old furnace taken out, the heat pump set and connected to the existing ducts, two duct runs made larger, start-up and testing. Taking the old oil tank out of service is separate.

Project overview

In this example, the owners of a 1950s house in Everett have an oil furnace near the end of its life and want cooling in summer too. The house already has ducts to every room, so a geothermal heat pump that blows warm or cool air can use most of them.

The back yard is too small for trenches, so the loop goes into two vertical bores. A heat loss calculation sets the size, about 3 tons here, and shows two duct runs that are too small for the new airflow. Those two are replaced; the rest stay.

The goal

The goal is one system for heating and cooling, sized for this house and using the ducts that were already there.

Process

1. First visit House and yard measured, ducts checked, heat loss calculated.
2. Before drilling Loop design done and the drilling notice filed with Washington Ecology.
3. Week one Drill rig in the back yard for two to three days; loop pipe set, grouted and trenched to the house.
4. Week two Old furnace out, heat pump set and piped, ducts changed, wiring done.
5. Week three Start-up, testing, the thermostat set up and a walk-through of the controls.

Planning right

• The heat loss calculation, not the floor area, decides the size of the system.
• An old oil tank has its own rules for taking it out of service. Plan it with the furnace removal.
• Check the electrical panel early. A heat pump may need a new circuit.
• Keep the drawing of the loop with the house papers before any future fence or patio.

Scope of work

A heat loss calculation, the loop design, three vertical bores with grouted loop pipe, the pipe run to the house, the heat pump set and connected to the existing ducts, start-up and testing, and the drilling pad cleared. Bores leave little garden damage, but garden repair is not included.

Project overview

In this example, the owners of a 1990s house on a small Snohomish lot want to replace a gas furnace and an air conditioner with one geothermal system. There is not enough open ground for trenches, so the loop goes down instead of across.

A drill rig sets up on a gravel pad beside the house and drills three bores. Loop pipe goes into each one and the space around it is filled with grout. The pipes join in a short trench to the house, where the heat pump takes the furnace’s place on the existing ducts.

The goal

The goal is one system for heating and cooling on a lot too small for trenches, with the loop out of sight.

Process

1. First visit Heat loss calculated, yard measured, buried lines marked.
2. Before drilling Loop design done and the drilling notice filed with Washington Ecology.
3. Days one to four Rig on the gravel pad; three bores drilled, loop pipe set and grouted.
4. Week two Short trench to the house, the old furnace and air conditioner out, heat pump in.
5. Last days Start-up and testing, the pad cleared and the yard tidied.

Planning right

• Bores need far less yard than trenches, but the rig needs a clear way in from the street.
• Call 811 before any digging so buried lines are marked.
• Drilling brings up mud and water. Plan where it goes before the rig arrives.
• Keep the drawing of the bore locations for future fences, patios or additions.

Scope of work

A heat loss calculation, the loop design, trenches dug across the lawn, the loop pipe laid, pressure tested and backfilled, the heat pump set in the utility room and connected, start-up and testing. Reseeding and garden repair are extra.

Project overview

In this example, the owners of a 2010s house on a large lot want to replace an electric furnace with geothermal heating and cooling. The lawn beside the house is open, flat and clear of trees, which makes trenches cheaper than drilling.

The loop pipe is laid in trenches about 5 to 6 ft deep, pressure tested and buried. The lawn is torn up for a short time, so the work is timed to let the grass grow back. The heat pump goes into the utility room by the back door.

The goal

The goal is heating and cooling from one system, with the loop out of sight under the lawn.

Process

1. First visit Heat loss calculated, the lawn measured and buried lines marked.
2. Week one Trenches dug, loop pipe laid and pressure tested, trenches backfilled.
3. Week two Old furnace out, heat pump in the utility room, ducts and wiring connected.
4. Last days Start-up and testing; topsoil leveled and the lawn reseeded.

Planning right

• Trenches need a lot of open ground. Most city lots suit bores better.
• Keep the loop away from trees, where roots and future digging can reach it.
• Plan the trenching for late summer or early fall so the grass can grow back before winter.
• Ask for a drawing of where the loop runs before the lawn is reseeded.

Scope of work

A room-by-room heat loss calculation, the tubing layout, the ground loop, a geothermal heat pump that heats water, manifolds, controls, start-up and balancing. Cooling, if wanted, is a separate design question.

Project overview

In this example, a family building a new two-story house in Monroe wants heated floors in every room. Because the house is still on paper, the ground loop, the heat pump and the floor tubing are all planned with the build.

The loop goes in while the site is open, and the tubing is laid before the slab is poured and before the upstairs floors are covered. A geothermal heat pump heats water for the floors. Cooling and hot water are planned separately, since floor heating alone does not cool the house.

The goal

The goal is even heat from the floors in every room, from a system sized for this house.

Process

1. Design stage Room-by-room heat loss, tubing layout and loop design done with the house plans.
2. Site work Ground loop put in while the site is open.
3. Before the slab Tubing fixed in place and pressure tested before the pour.
4. Framing stage Upstairs tubing laid under the floors, manifolds set in the mechanical room.
5. Before move-in Heat pump connected, the system filled, started and balanced room by room.

Planning right

• Planning floor heating before the slab is poured costs far less than adding it later.
• Floor heating warms slowly. It suits steady, even heat more than quick changes.
• Hard floors pass heat better than thick carpet. Choose floor coverings with the designer.
• Take photos of the tubing before the pour, so nobody drills into it later.

Scope of work

A heat loss calculation from the house plans, the loop design, the bores drilled while the site is open, the loop pipe brought into the house, the heat pump connected to the new ducts, start-up and testing.

Project overview

In this example, the owners of a wooded lot near Everett are building a two-story house and want geothermal heating and cooling from the start. It costs less to plan it with the house. The drill rig can reach the site before the driveway is paved.

The system is sized from the house plans, and the ducts are designed for the heat pump’s airflow from the start. The bores are drilled during site work and the heat pump goes in with the rest of the mechanical work.

The goal

The goal is a new house with geothermal heating and cooling built in, sized from the plans, with the loop placed before anything covers the yard.

Process

1. Design stage Heat loss calculated from the plans; loop and ducts designed with the house.
2. Site work Drilling notice filed; bores drilled in the gravel area and loop pipe set before it is paved.
3. Rough-in Loop pipe brought into the house; heat pump set and ducts connected.
4. Before move-in Start-up, testing and a walk-through of the controls.

Planning right

• Tell the builder early. The bores need a clear yard and the house needs a spot for the heat pump.
• Mark the bore locations on the site plan so the driveway and landscaping avoid them.
• Ducts sized for a heat pump work better than ducts sized for a furnace.
• If the plans change, update the heat loss calculation. The size comes from the final design.