Why households add an indirect tank
The most common reason is a tankless coil that cannot keep up. A coil heats water as it flows, with nothing stored, so two showers or a shower and a dishwasher can overwhelm it. An indirect tank stores a supply of hot water heated by the boiler, so the household draws from a full tank instead of a trickle of just-heated water.
Other reasons include replacing an old indirect tank that has failed, replacing a separate fuel-fired water heater so that one appliance in the cellar does the work of two, and adding hot water capacity when a household grows or a bathroom is added.
When an indirect makes sense, and when it does not
Good fit
- The boiler is sound and expected to stay in service for years
- There is room beside the boiler for a tank
- The boiler can take another zone for the hot water
- The household runs out of hot water with a coil
Think again
- The boiler is near the end of its working life
- The household is planning to move away from the boiler for heating
- There is no practical space near the boiler
- The boiler itself has unresolved problems
If the boiler's future is uncertain, it is worth reading hot water after a heating system change before committing. An indirect tank is tied to the boiler that heats it; when the boiler goes, the indirect usually needs a new heat source too.
Sizing an indirect tank
Indirect tanks recover quickly when the boiler has capacity to spare, so they can often be smaller than a standalone tank for the same household. Sizing still starts with the busiest hot water period in your home, how many bathrooms are in use at once, and whether there is a large tub. Cold inlet water matters here as everywhere in Connecticut, and on a well it matters year-round. The installer also considers how much output the boiler can devote to the tank. See our sizing guide.
What the installation involves
- Setting the tank beside the boiler, on a level base with room for service
- A boiler-side circuit of piping from the boiler to the tank's coil and back, with a circulator pump or zone valve
- Controls: a tank sensor or control wired so the tank can call the boiler for heat, often set so hot water is served first
- Household water connections: cold in, hot out, shutoff valves, and usually a mixing valve on the outlet
- A temperature and pressure relief valve with a discharge pipe to a suitable point
- An expansion tank on the household water side where the plumbing is closed, as on many well systems
- Dealing with the old setup: the old coil is either left in place and taken out of use, or the old water heater removed
The installer works on the hot water side and the connection to the boiler. It does not include repairing the boiler or changing the heating system.
An indirect is often the cure for a coil that cannot keep up.
On a private well?
Installing an indirect on a well system
Tell the installer about the well. They will plan for sediment with a drain valve that can be used for flushing, think about the tank's construction and anode arrangement, and check whether the plumbing is closed so an expansion tank is needed. Well water is also cold year-round, which feeds into sizing.
Living with an indirect tank
Once it is in, an indirect tank asks little of you. The boiler fires when the tank calls for heat, and the rest of the time the tank simply holds its water hot behind its insulation. You may notice the heating pause briefly during a long run of showers while the boiler tops the tank up; that is normal. What it does need is the same attention any storage tank gets: an eye on the relief valve and drain valve, and periodic flushing in a well home.
Fitting one into an old cellar
Boilers in older Connecticut houses are often tucked into corners of fieldstone or brick cellars with low beams and a single narrow stair. An indirect tank is a large object to bring down and set in place, and it needs room around it for its piping and for future service. Describe the space when you call. Sometimes a slightly smaller or differently shaped tank is chosen to suit the room, which the installer can explain.
Before and during the job
There is nothing to prepare on the boiler or plumbing, and nothing you should touch. Clear the area around the boiler and the route down, and keep the heating and hot water controls as they are. If hot water will be off for part of the day, the installer will tell you when.
What affects the cost of indirect water heater installation
| Factor | Why it matters |
|---|---|
| Tank size and type | Larger tanks and different constructions differ in equipment cost |
| Boiler connection | A simple zone addition is less work than reworking crowded near-boiler piping |
| Controls | Some boilers need additional controls to serve the hot water first |
| Access and space | Tight cellars and steep stairs add labour |
| Extras | Expansion tank, mixing valve and removal of the old water heater |
How long indirect water heater installation takes in Connecticut
A straightforward indirect installation beside an accessible boiler is typically completed in a single visit, with hot water and heating off for part of it. Crowded boiler piping, control changes or difficult access can extend that. The installer will set out the plan and timing before starting.
Get the plan and the timing laid out first.
Indirect installation questions
Can any boiler run an indirect water heater?
Most hot water boilers can, but not all setups suit one. The installer checks the boiler's condition, whether it can take another zone, its controls, and whether it has capacity to heat the tank without starving the heating. If it is not a good match, they will say so.
Will an indirect tank solve running out of hot water from a coil?
In most homes it makes a big difference, because the household draws from stored hot water rather than water heated on the fly. How big a difference depends on the tank size, the boiler and the household's habits, all of which the installer considers.
Our boiler is getting old. Should we still add an indirect?
Think carefully. An indirect relies on the boiler. If the boiler is likely to be replaced or removed before long, it is often better to plan the hot water alongside that decision, so you do not buy a tank that loses its heat source.
What happens to the old tankless coil?
Usually it is taken out of use and left in the boiler, with the hot water piping reconnected to the new tank. In some cases the installer may suggest a different arrangement. Either way, the boiler itself is not repaired as part of this job.
Does the boiler have to run in summer with an indirect?
Yes, it fires to heat the tank when the tank calls for heat, but it no longer has to stay hot all the time as it often does with a coil. It runs when there is hot water to make rather than idling to keep a coil ready.
Is an indirect tank a good choice on a well?
It can be. Plan for sediment with a usable drain valve, and allow for cold year-round inlet water in sizing. An expansion tank is often needed on well systems. The installer covers all of this.
Can the indirect go somewhere other than next to the boiler?
Close to the boiler is usually best, to keep the piping between them short and tidy. A different spot can work if there is a good reason, but it adds piping and cost. The installer can show you the options.
Do you install the boiler as well?
No. We arrange water heater work only, including indirect tanks and their connection to an existing boiler. Boiler installation and heating conversions are outside this service.