Tankless + Booster + Cold Start?

Mark_127

This is more of a "what if"/"why not" question, I'm not really trying to accomplish it on a live system.

I was thinking about indirect tanks compared to tankless coil systems with booster tanks, and it occurred to me that if you could run the indirect off of a cold-start boiler, there didn't seem to be a good reason you couldn't do the same with the booster tank.

From the perspective of the booster tank, the only difference would be that it would be pressurized by potentially cold water when the tank's thermostat wasn't calling for heat. But the indirect is always pressurized by cold water, right?

Seems like the indirect and the tankless+booster are, in principle, really similar except for where the heat transfer occurs. Would the size (surface area for heat transfer) of the tankless coil be a limiting factor here? Or is there something else I'm missing?

Unknown

It can be done

We've installed quite a few boiler / booster combos . I haven't cold started one yet , but we do use a triple aquastat maintaining the lowest setting . We also prioritize the booster tank .

I haven't timed the recovery on a booster in a while . I'll do one next time and see how it compares to a new boiler and indirect , same sizes . I know the EK 2000 heats up their 40 gallon tank in 13 mins ( from a job last week ) .

In my opinion I don't see a problem cold starting a system with a booster tank .

Robert O'Brien

How about?

a flat plate HX instead of the tankless? I've done it with a few Biasi B-10 oil boilers and it works just fine

bill nye_3

Warm Start ?

I am not an advocate of cold start because I service oil burners for a living. I see the damage it causes and the extra effort needed to clean it.

I like "warm start", anything above 100° F. I did a boiler with my brother at his house. I took out an old Burnham V-34 and "restored" it with two new tankless coils, a new burner and controls, and a new combustion chamber.

We piped the coils in series into a "used" system 2000 storage tank. The 8124 maintains 120° on the boiler and when the storage tank aquastat calls a switching relay starts the circ pump to the storage tank and starts the burner through ZR.

There are 6 people in the house, never a hot water issue. Since my Dad owned the house I think they went through at least 5 oil fired water heaters.