Adding an electric hot water tank to combi boiler

Scott M_3

Hi everyone. I have a Baxi combi boiler that was installed about 9 years ago. During the summer I disconnected it to do some work so I temporary installed a 38 gallon electric water heater so we would still have hot water. After doing this I realized how much I dislike the tankless hot water part of the boiler. Same common problems as most units, delay in hot water getting to sinks, water temp fluctuates at first, etc. I know the best thing to do would be to install an indirect tank but that's not in the budget right now. I live in Massachusetts and the electric rates are high compared to natural gas so I was wondering if putting the electric tank in line after the boiler might make it more cost effective. I figure I could set the hot water out of the boiler a little hotter than the electric tank and then the tank would act as a storage tank. And it would only need to turn on the keep the water temp maintained throughout the day. The hot water tank is already paid for so the only cost is a few fittings and my time. Wondering if this is a waste of time since I might not be really saving any money doing this setup. Thanks for any help or comments.

Jamie Hall

Probably should work just fine. How much you save will be a complicated function of how you use hot water and the quality of the tank and so on... but it will surely save some, and will help with the problems of the tankless.

hot_rod

that will work, the electric will do most of the standby loss, get an extra insulation jacket for it to limit the cycling. I think the home stores still sell those vinyl fiberglass wrap kits.

The DHW in my shop is via a plate HX. Solar and a wood fired boiler keep it hot. I added a 12 gallon electric tank downstream and it takes that delay out and provides enough DHW for a shower if the plate HX is off.

I went with a 12 gallon because it is 120V, easy to plug and go.

njtommy

It will work absolutely fine pipe in series with each other. I would just set them for the same temp.

I always let people know about the delay of hot water when installing a combi boiler or tankless hot water heater. Honestly it drives me insane waiting for hot water.

hot_rod

Hearing that thing spool up and down every time you crack a faucet drives me crazy.

I think my dishwasher completely fills with cold water, since it takes so long to fire up and supply to the faucet.

njtommy

I really won't hear mine spool up unless I turn the tub on. So that's a plus.

Another thing that drives me nuts is hearing the condensate pump run while lying in bed at night. Lol. To make it worst I have two of them on for the humidifier and the other for the combi boiler. Lol.

I will open up the hot side before starting the dish washer then once it's hot I start the dish washer. Is a giant waste of water. Really want to install a hot water recirculating pump and small electric tank under the kitchen sink. Maybe this winter I will get around to it

Big Ed_4

You want to install the tank after the tankless ..Just in series after the combi incoming hot water would just dilute into the tank .....r ... You would need an pump that would give you enough flow to turn on the combi and build up an storage of an average temp making an aqua booster... or pipe the tank before the combi and pre warm the water . Which is good in cold climates when the incoming water gets too cold in winter ....