Does a DHT indirect work with an oil boiler?

Yes. DHT says Techtanium works with any hydronic heat source, and its ratings assume 180 degree boiler water, which oil boilers commonly supply.

Which DHT indirect lasts longer, Techtanium or TX?

DHT backs the TX with a residential limited lifetime warranty, versus 7 years for Techtanium. The TX is stainless with no anode to wear out.

How big a boiler do I need for a DHT indirect?

It depends on the tank. DHT lists 120,000 BTU for the TT-40 and TX-40, 140,000 for the TT-55, and 180,000 for the TT-79 and TX-80.

How often should a DHT indirect be serviced?

At least once a year. DHT recommends flushing every six months, plus yearly anode and relief valve checks on Techtanium tanks.

What's the difference between DHT TT and MP models?

Connections and size. TT models have side connections and run 40 to 119 gallons. MP models have top connections and run 20 to 50 gallons.

DHT Indirect Water Heaters Long Island

Indirect Water Heater Brand

About DHT Indirect Water Heaters

You get faster showers and a boiler that can rest in summer. We install, repair and service DHT indirect water heaters across Long Island, Nassau and Suffolk Counties, and we stock the common parts. Domino Fuel is family-owned since 1981 and runs 24/7 emergency service.

Diversified Heat Transfer, or DHT, has made heat exchange equipment since 1938 and works out of Towaco, New Jersey. It also builds replacement tankless coils for dozens of boiler brands. It also sells Sussman electric boilers.

DHT now offers two very different indirect tanks. Techtanium is a glass-lined steel tank. The TX Series is a welded stainless tank with no anode rod. For DHT's coils and Everhot heaters, see our page on DHT water heaters and tankless coils.

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All Models Serviced

Good to Know

How a DHT Indirect Works With Your Oil or Gas Boiler

A DHT indirect has no burner. Boiler water flows through a coil inside the tank and heats the drinking water around it, and the two never touch. When the tank's aquastat calls, the boiler fires and a circulator or zone valve sends hot water to the coil.

DHT rates its tanks with the boiler holding 180 degrees, which a typical Long Island oil boiler or gas boiler can do. DHT also recommends a priority control so the boiler can keep its temperature while the tank recovers. Its manual warns that a zone valve without a full bore can cause a high pressure drop and hurt performance.

Model Lineup

DHT Indirect Water Heater Models We Install and Service

Techtanium is titanium glass-lined steel with magnesium anodes, two in TT models and one in MP models, and it comes in more sizes. The TX is welded 444 stainless steel. Ratings below come from DHT's data sheets at a 90 degree rise, and boiler BTU is the size DHT says the boiler needs.

Model	Gallons	First Hour Rating	Boiler BTU Needed	Good For
Techtanium MP-32	31.7	165 gal	95,000	Small homes, top connections
Techtanium TT-40	40	188 gal	120,000	Two-bath homes
Techtanium TT-55	55	226 gal	140,000	Families with teens
Techtanium TT-79	79	296 gal	180,000	Large tubs, recirculation
TX-40	40	210 gal	120,000	Two baths, no anode upkeep
TX-80	80	336 gal	180,000	Bigger homes

Long Island Homes

DHT Indirect Water Heaters for Long Island Homes

Match the tank to the boiler first. A TT-40 calls for 120,000 BTU, and a TX-110 calls for 199,000. If your oil boiler is small, a smaller tank or an MP model makes more sense than the biggest tank on the list.

Long Island homes on wells or with harder water see more scale. DHT's TX tank is passivated for high-chloride water and needs no anode, while Techtanium relies on magnesium anodes you should inspect. The MP Series puts all its connections on top, which helps in a tight utility closet.

Many local oil boilers still make hot water through a coil inside the boiler. Moving that job to a DHT tank lets you set the boiler up for heating only, and the tank holds heat well between calls.

Warranty

DHT Indirect Water Heater Warranty

DHT's Techtanium manual lists 7 years for residential use and 3 years for commercial use, with 1 year on parts. DHT counts a tank as commercial if it's ever run above 150 degrees. The owner is expected to have the anodes checked yearly, and DHT says skipping that can void the warranty.

The TX Series carries a residential limited lifetime warranty, 8 years commercial and 5 years industrial. Registration for Techtanium is on DHT's site.

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

Compare Brands

DHT vs Bock Indirect Water Heaters

DHT Techtanium and the Bock SideKick are the closest match: both are glass-lined steel tanks protected by magnesium anodes. Bock's lining is a cobalt-enriched C-Glass, and DHT's is titanium glass. The big gap is warranty. Bock offers limited lifetime residential coverage when the tank is registered at install, while Techtanium carries 7 years.

DHT's answer to that is the TX Series. It's 444 stainless with no anode and its own residential limited lifetime warranty. For homes with aggressive water, or owners who don't want anode checks, the TX is the stronger pick. Compare the Bock SideKick indirect for the full rundown.

Repair & Service

DHT Indirect Water Heater Repair and Service

Here's what usually goes wrong, and most of it is on the boiler side of the tank.

Tank won't get hot: the boiler isn't reaching temperature or the aquastat has failed.
Short bursts of hot water: the tank is larger than the boiler can support, or there's no priority control.
Heat works but no hot water: a failed zone valve, circulator or relay on the indirect zone.
Relief valve weeping: no expansion tank, or the T and P valve needs replacing.
Sulfur smell in a Techtanium: a worn magnesium anode.
Gritty water or slow fill: sediment in the tank bottom.

Good to Know

DHT Indirect Tune-Up and Parts

We stock the common parts, including aquastats, circulators, zone valves, T and P valves and mixing valves. DHT suggests flushing the tank every six months, inspecting the anodes at least every 12 months, and testing the relief valve every 12 months. We fold that into your yearly boiler service.

Installation

DHT Indirect Water Heater Installation and Replacement

Price depends on the tank line and size, the piping and controls, removing the old heater, and code items. Call for a quote.

We confirm your boiler's BTU output and size the DHT tank to it.
We set the tank and pipe the boiler coil on its own zone.
We add a priority control when your system allows it.
We pipe the domestic side with a T and P valve, expansion tank and mixing valve. DHT calls for a mixing valve when you want water hotter than 119 degrees.
We wire the aquastat, fire the boiler and check every connection.

DHT Indirect Water Heater Installation and Repair on Long Island