Bellingham & Whatcom County
Guides written for houses that actually exist here
Sizing, permits, panel capacity, zone planning and maintenance — with the local numbers, the local permit desks and the local water in them.
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Every guide
Long-form and specific. Read the one that matches your decision, or call and skip to the answer.
How to size a heat pump in Bellingham
Sizing is the decision that determines whether you like your heat pump. Bellingham’s code heating design temperature is 19°F at station "Bellingham 2 N" in WAC 51-11C-80100, five degrees colder than Seattle-Tacoma’s 24°F, and our cooling design temperature is 78°F in a climate zone that is heating-dominated. That combination means the equipment has to make real heat on a cold January night and then turn down almost to nothing through a long, mild shoulder season, and a system chosen by square footage will do exactly one of those two jobs.
7 sections Read the guide →
Heat pump buying guide for Whatcom County
Buying a heat pump in Whatcom County in 2026 involves three decisions that most shoppers make in the wrong order: what your incentives actually are, whether your house wants ducted or ductless equipment, and only then which brand and model. The incentive picture here is unusual. The federal tax credit is gone, PSE’s big conversion rebate depends entirely on what fuel you heat with today, and the gas-side rebates that dominate Seattle-area advice do not apply because Cascade Natural Gas rather than PSE is the gas utility.
8 sections Read the guide →
How to plan mini split zones
The most common mini split regret is a zone plan that looked fine on paper. A wall-mounted head conditions the air it can reach, which means the useful question is not how many square feet you have but how many separately closed spaces you expect to keep comfortable. Walk your own floor plan before anyone quotes it, and the quotes you get back will be comparable.
7 sections Read the guide →
Where to put the outdoor unit
The outdoor unit location is decided in about four minutes on a site visit and then lives with you for fifteen years. Get it right and the unit breathes freely, drains properly, stays out of the leaf fall and the snow line, and does not annoy anybody. Get it wrong and you get a coil packed with fir needles by November, a defrost cycle standing in its own ice, or a complaint from the neighbour whose bedroom window is eight feet away.
6 sections Read the guide →
Heat pump permits: City of Bellingham
A heat pump installation is permitted work. Inside Bellingham city limits the mechanical permit comes from City of Bellingham Building Services, filed through the city’s eTRAKiT online portal, and any electrical work is separately permitted by a licensed electrical contractor. The step almost everyone skips is checking whether the address is actually inside city limits. A great many mailing addresses that read "Bellingham, WA" sit in unincorporated Whatcom County — the City says so explicitly — and that changes the permit authority, the fee schedule and the inspector.
6 sections Read the guide →
Heat pump permits: unincorporated Whatcom County
If your property is outside an incorporated city, the mechanical permit for a heat pump comes from Whatcom County Planning and Development Services rather than a city building department. That covers a large share of the addresses we work at: the foothills and the Mount Baker corridor, the farmland north and east of Lynden, Birch Bay, Sudden Valley, Geneva, Marietta-Alderwood, Lummi Island and Point Roberts. It also covers a substantial number of properties whose mail says "Bellingham." County jurisdiction brings its own considerations — larger parcels with different setbacks, wells and septic to keep clear of, snow load at elevation, and access questions that affect scheduling.
6 sections Read the guide →
Electrical requirements for a heat pump
The electrical scope is where heat pump projects surprise people, and it is also the part we do not perform. All electrical work on our projects is performed and permitted by a licensed electrical contractor, and Bellingham Heating and Cooling does not hold an electrical contractor licence. What we do is coordinate that scope, sequence it with the mechanical work, and make sure you know what it involves before you sign anything. A heat pump needs a dedicated circuit sized to the equipment, a service disconnect within sight of it, and correct conductor and overcurrent protection. Pre-1960 Bellingham stock on 100-amp service sometimes needs a service upgrade to carry that, and removing electric baseboard can free up the capacity instead.
6 sections Read the guide →
HSPF2, SEER2 and COP explained
Efficiency ratings exist so you can compare equipment, and they get quoted at you in ways designed to end conversations rather than inform them. There are three numbers worth understanding. HSPF2 is a seasonal heating efficiency; SEER2 is a seasonal cooling efficiency; COP is instantaneous efficiency at a stated outdoor temperature, and it is the one that tells you what happens on a cold Bellingham morning. All three changed meaning in 2023 when the M1 test procedure replaced the old one, so old and new numbers are not interchangeable.
6 sections Read the guide →
Heat pump maintenance schedule for a marine climate
Most heat pump maintenance advice is written for dry climates, and it does not describe what happens to equipment here. In Whatcom County the outdoor coil collects Douglas fir and cedar needles, maple leaves, moss and, within reach of the water, salt. The indoor side collects whatever is in the air, which in August includes wildfire smoke. None of that is exotic, but it does change the cadence: coil cleaning matters more here than filter changes do, and on a waterfront property a fresh-water rinse is genuinely useful rather than a make-work item.
6 sections Read the guide →
How to claim the PSE heat pump rebate
PSE’s heat pump rebates are the largest incentive most Whatcom County households can actually claim, and they work differently from the tax credits people expect. They are contractor-gated: PSE requires the installing contractor to be in its network, states that you may not use an out-of-network contractor or complete the work yourself, and applies the credit to your project rather than mailing you a cheque. That has a consequence worth stating up front: ask us to confirm our PSE network status for your specific project before you count the rebate as money in hand.
6 sections Read the guide →
Wildfire smoke and your HVAC system
August in the Pacific Northwest now regularly brings days of wildfire smoke, and the equipment in most Bellingham houses was not chosen with that in mind. The mechanical response is straightforward once you separate the three jobs: keep smoke out of the building, filter what is already inside, and stay cool enough that you are not tempted to open a window. A window air conditioner is a hole in your envelope during exactly the wrong week. A ductless mini split lets you keep the house closed but has thin filters. A central ducted system is the best filtration platform you can own.
6 sections Read the guide →
Test your well before you buy filtration
The most expensive mistake in residential water treatment is buying equipment before you know what is in the water. Carbon does not remove nitrate. Reverse osmosis is not disinfection. A softener does nothing about iron staining. Each of those is a different problem with a different answer, and the only way to know which you have is a laboratory test of your own well. In Whatcom County the questions worth asking depend on where you are: agricultural land around Lynden, Everson, Nooksack, Sumas and Custer raises nitrate as a real question, while foothill and lakeside wells more often produce iron, manganese and hardness.
6 sections Read the guide →
Why local guides beat national ones
A national sizing article uses a national design temperature. Bellingham's is 19°F — colder than Sea-Tac's 24°F — in climate zone 4C (marine), which is heating-dominated, damp and rarely below 10°F. Every number in these guides is worked against that.
Permits work the same way. Whether your mechanical permit comes from City of Bellingham Building Services or Whatcom County Planning & Development Services depends on which side of the city line your address sits, and a great many "Bellingham" mailing addresses are in unincorporated county.
Would rather just ask?
Send us the house and the problem. We will point you at the part of this that matters and leave the rest alone.
Ready for a straight answer on your house?
Tell us what you have now and what you want it to do. We will tell you what fits, what it costs, and which rebates you actually qualify for — before anyone comes out.
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