Electric water heater / Buffer tank

Snowmelt

Existing electric water heater Bradford while , I think 32 gallons , can I use that for a Buffer tank with the hot cold for the space loop & the pressure relief tapping and the drain valve tapping for the boiler loop. Of course I would tee it and put the relief valves and the drain on a tee.

pecmsg

So the water heater will be used as a boiler?

MikeAmann

If you are thinking what I think you are thinking, then NO, there is no separate coil inside of that water heater. It's a tank of water.

WMno57

Mike and pecmsg, He is not thinking what you think he is thinking. The key word here is "Buffer" in the title. I am thinking it will work.

Snowmelt

Mr 57, how would that be piped

Snowmelt

Yes it will be used as a boiler although they are doing it wrong it’s acting as a boiler now with no P/S

Hot_water_fan

Why a four pipe buffer tank at all? You could do a two-pipe buffer tank too.

MikeAmann

OK, enlighten me with a diagram.

Hot_water_fan

Easier with a purpose built buffer tank I’d assume. 

Snowmelt

So let the water just heat up bottom of tank so it’s in series with the pumps

WMno57

I'm not a Pro, this is my guess (greater than sign ">" shows flow direction).

Boiler Loop
Boiler Secondary Supply > Water Heater Drain Fitting
Water Heater PRV fitting > Boiler Secondary Return

Space Loop
Water Heater Hot > Space loop input
Space Loop output > Water heater cold

hot_rod

What type of flow rate are you considering? You are limited by the 3/4” taps, or the element holes

Ive connected the two top with fip tube removed. For your bottom, you are limited to the 3/4 drain port. I use a 3/4 male C 1-1/4 copper adapter yeti increase quickly

You can also use the element holes, typically 1”, you give up some tanks use ability as the are not top and bottom, 6 or so “ up and down, but a large connection, if you are needing 8 gpm or more, use the element holes

Same method a 1” make X 1-1/4” copper adapter.


Here are a few that I have built. That Viessmann one was 10 or so
years ago

The small 6 gallon has a 4500w element for a 15,000 btu backup heat source

WMno57

I think this would be better though:

Single Loop
Boiler Secondary Supply > Space Loop Input
Space Loop Output > Water Heater Cold
Water Heater Hot > Boiler Secondary Return

WMno57

What is the space loop? Will the boiler be heating any other loops? Now or future?

WMno57

The disadvantage to all this is you get the blame if there is a failure in the existing water heater.
Is the reason for doing this increased buffering capacity or gaining redundant heat sources (WH + Boiler)? Are those benefits worth the additional points of failure?

pedmec

If your in Massachusetts the water heater as to be specifically design to be used as a heating and domestic hot water source and approved for that purpose by our plumbing board. We replace these type water heaters all the time and its not cheap. These are not long term solutions to your heating system.

These are installed in managed property. We work with the property manger to replace these. The property manager has something like 500 units in multiple locations with the approved water heaters but we are constantly replacing them. As a developer they are cheaper to install initially but the owners pay dearly in replacements.

Use the proper materials and equipment for safe operation of your heating system.

hot_rod

Thermo 2000 makes such a product 

Snowmelt

The house is sprayed foamed really good. The boiler is large, but I’m going to say no more then 75 total, also he has 2 radiant floor 1 heated rad and 3 high temp. Later I will ask the btu for the high temp. But I know the low temp is 20-30 thousand btu. I can either do what hot rod said do a 3/4 male to 1 inch male. I know there’s less then 100,000 btu for whole house.

Snowmelt

What’s there now

hot_rod

What is your goal for the buffer tank? Longer boiler cycles?

Snowmelt

Yes he has small zones. Even a towel warmer as a zone , but as you can see it’s not the most organized job