Commercial · Residential | Plumbing · Heating · Cooling
Commercial Plumbing, Heating & HVAC for NH, MA & ME
Plant rooms, food plants, and facilities across three states, run by a master plumber with 21 years in the trade. Homeowners get an honest range in 90 seconds, rebates off the top.
Licensed local. Good rep.
The credentials are printed, not implied
- 21+
- Years in the trade
- 3
- States licensed: NH, MA, ME
- 7
- Licenses held
- Mitsubishi Diamond Contractor
- Master Plumber
- Fully Licensed & Insured
License register · NH / MA / ME
New Hampshire
- NH PL M-2210287
- NH GF2212147
- NH-MBE2201473
Massachusetts
- MA PL M-17020
- MA HIC 207892
- MA PL CORP-4668
Maine
- ME PL MS-90020494
Every number above is on file with its state board. Verify any of them with the NH, MA, or ME licensing office before you hire anyone, including us.
Commercial & mission-critical
The plant rooms speak for themselves
Seven of every ten JP Karos jobs are commercial: boiler plants, process gas, commercial hot water, multi-residential mechanical. One accountable master plumber, three states.
Multi-boiler plant rooms
Three-boiler oil plant with a twelve-circulator header, built clean and serviceable.
Process gas in live facilities
Permitted gas piping feeding production equipment in a working food plant.
Commercial hot water
Commercial water heaters installed and wired for restaurants and facilities.
Property portfolios across state lines
One licensed vendor for NH, MA, and ME holdings: per-property records, one invoice, the same crew at every address.
For homeowners · First on the seacoast
Know your number in 90 seconds
Tell the estimate engine what's in your basement and what you want instead. In about a minute it shows Good and Best equipment options with real monthly pricing, your honest installed range, and your state's potential rebate range taken off the top.
- Tell us about your home and system
- See Good and Best options with monthly pricing
- Watch the potential rebate come off the top
- Pick a morning for the home visit
Typical seacoast range
Ranges reviewed July 2026
- Gas boiler swap
- $8,800 to $23,400 installed
- Single-zone mini split
- $4,400 to $11,400 installed
- Whole-home heat pump
- $17,600 to $44,400 before rebates
Premium-equipment seacoast ranges, confirmed at your site visit. Written quotes regularly land inside or below the band.
Are you looking for a repair or a replacement?
Repairs are diagnosed on site. Replacements get an instant range right here.
About 90 seconds. No phone tag.
What we do
One licensed crew for the whole system
Commercial mechanical is the backbone of the book. Heat pumps are the residential flagship. Gas, water, and plumbing round out the trade.
Heat Pumps & Mini Splits
Mitsubishi H2i systems installed by a Diamond Contractor, sized for New England winters. Wall units or flush EZ FIT ceiling cassettes, one system that cools all summer and heats deep into the negatives, with your existing boiler kept as backup where it makes sense.
Price a Mini Split
The promise
Built to be the opposite of the 1.8-star giants
The big consolidators run coupon walls, call centers, and upsell scripts. Here's what homeowners and facility managers get instead.
Gauges you can read, numbers you can check.
Published ranges. Real numbers.
The quote you can see
Everyone else makes you book a visit just to hear a number. We publish ours, and the engine shows yours in 90 seconds.
The math, in the open.
The rebate is your discount, not our markup
You see the gross price, the rebate range for your state, and the math between them. Check every line.
NH. MA. ME. One roof.
One license holder for every address
Master plumber licensure in NH, MA, and ME under one roof. One accountable contractor for every address on your list.
Diagnose first. Replace last.
If it can be fixed, we fix it
We diagnose, show you the evidence, and replace only when repair stops making sense. That is how 21 years of rep gets built.
Where we work
One call, three states
Based in East Hampstead, moving to the Portsmouth area, and licensed across the border in every direction: the NH seacoast and Lakes Region, northeastern Massachusetts, and York County Maine. Facilities and property portfolios ride the same routes as the homes.
New Hampshire
Seacoast to the Lakes Region: Portsmouth, Dover, East Hampstead, and the towns between.
NH Service Area
Massachusetts
Merrimack Valley and northeastern MA: Haverhill, Methuen, and Mass Save territory.
MA Service Area
Before the first no-heat night
Swap the oil boiler before it picks the coldest week to quit
Boilers fail in January, not July. Swap now and you choose the equipment, the schedule, and the price, with this year's rebate programs still open and the crew booked on your terms.
- Stop wincing at the oil bill: heat pump conversions and high-efficiency swaps
- Planned install now beats emergency rates in a cold snap
- Current-year rebate windows close with the calendar. We verify yours before you sign
Program rates verified July 2026. Eligibility confirmed before you sign.
Big-ticket work, sane monthly numbers
Most system swaps here are financed. We show every monthly figure with the APR and term right beside it, computed from one amortization formula, so the number you see is the number the paperwork says.
Massachusetts homeowners: the Mass Save HEAT Loan offers 0% financing from $500 to $25,000 for up to 7 years on qualifying heat pump work. Program rates verified July 2026, eligibility confirmed before you sign.
Monthly figures are examples computed at the displayed APR and term, subject to credit approval by the lender. They are illustrations, never quotes.
What customers say
The quote is straight. The reviews read like it.
Real jobs across NH, MA, and ME: burst pipes fixed the same day, boiler swaps that landed on the number, and floors left cleaner than we found them.
4.7★★★★★
Sample rating, shown until our Google reviews go live
Read All Reviews
“A pipe burst at my apartment and they came out the same day. Fixed it fast, cleaned up after, and the price was fair. Would absolutely call again.”
Verified customer
MapQuest review · burst pipe repair · 2025
“Two other companies wanted a home visit just to give a number. I used the online estimate on a Sunday night, had a real range in minutes, and the install crew showed up when they said they would. House is finally cool upstairs.”
Sarah T.
Portsmouth NH · mini split install · June 2026
“I manage units on both sides of the border and juggling two contractors was a headache. One no-heat call in January, they were out that day, invoice was clean, and now they have all my properties.”
Dana R.
Property manager · Haverhill MA · January 2026
Straight answers
The questions we get, answered in the first sentence
Rebate math, sizing, and swap costs for NH, MA, and ME. Every article opens with the answer, then shows the work.
Ready to turn the range into your number?
Plug in what you have. See the range, the rebate, and the monthly line. Then pick a morning that works.
- 21+
- Years in the trade
- 3
- States licensed
- 7
- Licenses held