Hot water coil with electric hot water tank?

Ken_40

What you have is not that strange.

Generally, (assuming the boiler is NG) gas is cheaper than electric. So, the boiler making D/H/W in winter, when the boiler would typically be on anyhow from time to time, is not that bad a design. Typically, the coil would heat the incoming water to say 150F, while the electric water heater would keep it at ~130-140 while being stored therein?

The cost of electric vs. gas vs. oil vs. the efficiency of each - and by season, is the real issue. Most steam boilers get ~80% efficiency. Standby losses are a significant issue as well.

Timers, that only allow the d/h/w generation to happen twice a day; say from 5 a.m. to 9 a.m., then from dinner time to last shower/bath of the day time - are very inexpensive to install, yet frequently overlooked most of he time. Maintaining hot water at 3 a.m. is pure waste.

You're onto something, but the solution is wildly diverse in any form. A programmable stat for the coil circuit and lowered electric 'stat settings may be the answer.

The classic answer?

"It all depends."

Matt_45

hot water coil with electric hot water tank?

I moved into an old house built in the 30s. It has a newer steam boiler with hot water coil and an eletric hot water heater piped in parallel. What is the best way to effectively disconnect the hot water coil to prevent the boiler from short cycling? There is a valve to shut off the coil hot water outlet. Should I turn the coil thermostat down as well? It's set at 180. Why is this piped this way? It seems counter-intuitive to have redundant systems in parallel. It seems like neither one will ever work efficiently this way. Thanks. Anyone think I should disconnect the tank and use the coil? Thanks again.

Matt_45

it's oil

It's an oil fired boiler. If I wash dishes or even just my hands it comes on. That's why I'm leaning towards shutting the coil off. I know how to shut the water tank off. How would I shut the coil off? Just shut off the hot outlet so water remains inside? Turn the thermostat down or off? I don't think both systems should be running in parallel. Why store hot water when the coil is providing it? Thanks.

Ken_40

Well...

It seems, the hookup is fraught with minor mistakes. The simple answer is, do what you think.

The correct answer may be: You already own most of what should be there. The fact that water pressue alone, without a circ. pump, is transferring D/H/W from the tankless coil to the storage tank, also acting as a water heater, is incorrect, is just one of many small issues - which collectively are completely innapropriate - is causing the problems you correctly mentioned.

Were it my house, and my cost per gallon of oil vs. cost per KW electric, I'd use the water heater as an indirect storage heater, put in the required controls and a circulater for winter and summer, and put a timer on it. Unless # 2 oil goes to $2.40/gallon or more, I'd use the boiler as the maker, not the electric W/H. I might leave the electric water heater at a low (say 120F) standby setting, so i would always have a shot of warm water, but I must agree, the way it is now becomes "short cycle city" - and that's not good.

Leo

Some boilers

Given you have an oil boiler it is best to keep it warm to keep it cleaner and you have a good set up to do this with. Is the electric hooked up, if yes I would un hook it. I would also use a circulator if you don't have one to keep the water warm by circulating it through the coil and tank. Some boiler brands are worse than others and if allowed to get cool especially in the summer they will plug up causing a service call.

Leo