Does DHT make regular gas or oil water heaters?

No. DHT doesn't make water heaters with their own burners. Its home products are tankless coils, external tankless heaters and indirect tanks, and all of them use heat from a boiler.

Can DHT replace the coil in my oil boiler?

Very likely. DHT's coil list covers Burnham, Weil-McLain, Peerless, Utica, Slant/Fin and many other boiler makes. We match it by your boiler's make and model.

Should I replace my tankless coil or add an indirect tank?

It depends on the boiler and your hot water use. A new coil is the quicker fix. An indirect tank gives stored hot water and lets the boiler rest between calls.

Who makes DHT water heaters?

Diversified Heat Transfer of Towaco, New Jersey, in business since 1938. Its site also carries Sussman electric boilers.

DHT Water Heaters and Tankless Coils Long Island

Water Heater Brand

About DHT Water Heaters

A new coil can bring your hot water back without replacing the boiler. We install, repair and service DHT water heaters and coils across Long Island, Nassau and Suffolk Counties, and we stock the common parts. Domino Fuel is family-owned since 1981, licensed and insured, with free estimates.

Diversified Heat Transfer, or DHT, has been in business since 1938 and builds heat exchange equipment for homes, businesses and industry in Towaco, New Jersey. Its site also carries Sussman electric boilers. DHT's site doesn't name a parent company.

DHT doesn't build gas or oil water heaters with their own burners. Everything it makes for home hot water uses heat from a boiler. That's why DHT matters on Long Island, where so many homes heat with an oil boiler that also makes the hot water.

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All Models Serviced

Model Lineup

DHT Water Heater and Coil Models We Install and Service

DHT's home lineup falls into three groups. Each one uses boiler water in a different way.

DHT Product	What It Is	Good For
Central Tankless Coils	Copper Tru-Fin coil that bolts into the boiler	Replacing a worn coil in an oil boiler
Lindy Tankless Coils	Coils built to OEM specs for low-pressure steel boilers	Older or hard-to-match boilers
Everhot External Tankless	Copper-shell heater mounted outside the boiler, 4 to 125 GPM	Larger homes and commercial use
Techtanium TT and MP	Titanium glass-lined indirect tank, 20 to 119 gal	Stored hot water from a boiler
TX Series	444 stainless indirect tank, 40 to 110 gal	Stored hot water with no anode to replace

Want the details on the tanks? See our page on DHT indirect water heaters.

Long Island Homes

DHT Tankless Coils for Long Island Oil Boilers

A tankless coil sits inside the boiler, surrounded by hot boiler water. Cold water runs through the coil and comes out hot, with no storage tank at all. DHT says it has the most extensive line of residential tankless coils in North America.

DHT's coil list covers boilers from American, Burnham, Crown, Dunkirk, H.B. Smith, Peerless, Slant/Fin, Utica, Weil-McLain and dozens of others. DHT rates its coils for a rise from 40 to 140 degrees with 200 degree boiler water. If your boiler is an older steel model, DHT's Lindy line builds coils to original OEM specs, which helps when the boiler maker's own part is hard to find.

Coils do wear out. Hard water leaves scale inside the tubes, and flow drops. Sometimes a new coil is the right fix. Other times, adding an indirect tank is the better long-term move, and we'll tell you which.

Good to Know

DHT Everhot External Tankless Water Heaters

The Everhot is a tankless heater that mounts outside the boiler instead of inside it. It has a solid copper shell with finned copper tubing and comes in vertical and horizontal styles. DHT rates the Everhot line from 4 to 125 GPM and sells double-wall versions too.

Warranty

DHT Water Heater Warranty

Warranty depends on the product. DHT lists a three-year warranty on Everhot external tankless heaters. Techtanium tanks carry 7 years residential and 3 years commercial, and the TX Series carries a residential limited lifetime warranty.

DHT's general limited warranty runs 12 months from shipment, covers parts only and excludes labor. Keep your paperwork and ask us which terms apply to your unit.

On top of the manufacturer's coverage, Domino backs every installation with a 1-year labor warranty.

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DHT Water Heaters vs Bock Oil-Fired Water Heaters

Both serve oil-heat homes, but in opposite ways. Every DHT product borrows heat from a boiler, so you need a boiler to use one. A Bock oil-fired water heater has its own burner, so it also works in homes heated by an oil furnace.

If you already have an oil boiler, a DHT coil or indirect tank means one less burner to service. If you have a furnace, or want hot water with the boiler shut off, a stand-alone Bock is the better fit.

Repair & Service

DHT Water Heater and Tankless Coil Repair and Service

Most DHT service calls on Long Island involve a tankless coil in an oil boiler.

Showers go from hot to cold: too much flow for the coil, often a missing or failed flow restrictor or mixing valve.
Low hot water pressure: scale is building up inside the coil tubes.
Water leaking at the coil plate: the coil gasket has failed.
Boiler losing water or pressure creeping up: the coil may be leaking inside the boiler.
Hot water slow to arrive: the boiler aquastat is set too low or the burner needs service.

Good to Know

DHT Coil Descaling and Parts

We stock the common parts, like coil gaskets, mixing valves, flow restrictors, aquastats and relief valves. Scale can sometimes be flushed out with a descaling pump, which buys time on a coil that isn't leaking. We usually do it during your yearly boiler service.

Installation

DHT Water Heater and Coil Installation and Replacement

Price depends on the coil model, how hard the old bolts are to free, any valves that need replacing and whether you'd rather add an indirect tank. Call for a quote, or start with our water heater repair service.

We read the boiler's make and model so we can match the right DHT coil.
We shut off and drain the boiler down below the coil.
We unbolt the old coil and clean the mounting face.
We install the new coil with a new gasket, then reconnect the piping, mixing valve and flow restrictor.
We refill, bleed air, fire the boiler and test hot water flow at a tap.

DHT Water Heater and Tankless Coil Installation and Repair on Long Island