I want to run a hydronic loop off of my hot water heater

Louis Ramirez

yes i did a heat loss on the room and it came out to 2,880(BTU/HR)know can any one tell me how to do the sizing for the HX

Room height 8'
Room lenght 30'
Room width 30'
No window
and it is 8'underground

Louis Ramirez

hydronic loop off of my hotwater heater

I would like to run a hydronic loop off of my hot water heater to heat about 40' of baseboard can any one tell me
what I need

Joe Brix

You need a real boiler

You plan on still needing domestic HW out of the WH? Flat plate heat exchanger. But what good will the BB be if you only run it at 140°, not 180°? Turning up the heat on the HWH will realy shorten its life and give you bad efficency.
Plus now you need to get a tempering valve to bring the domestic HW back down to 120°.

Get a seperate boiler/tankless WH that's OK'd by the manufacturer for heating.

Louis Ramirez

I only need 3,000 Btu's for the space

Joe Brix

75 BTU's per foot?

I guess a small flat plaxe HX could work. Bronze pump to circ the water from hot outlet supply thru HX to boiler drain.

Robert O'Connor_12

Louis

Have you done a heat loss calculation on the space? If so, how did you arrive at the number(s) you came up with, and at what temperature are you gonna run it at? On the post you made above, you claim the space needs only 3000Btuh, but 3/4" finned tube X 40' equates to much more than this. Check your numbers again OR come back and give us more details about the space.

If you insist on running it off the water heater (as Joe indicated) use a heat exchanger. I think I know where your comming from in regards to up front costs BUT you will give this money you saved right back to the utility because the water heater is in fact very wasteful energy wise.

Robert O'Connor/NJ

Alan(CaliforniaRadiant)Forbes

You won't

get much heat from BB using low water temperatures from a water heater; it's best to use a panel radiator (like Runtal or Panel Radiator brand) via a heat exchanger (HX). They are better suited for low water temperatures.

This is a picture of a HX off a water heater for radiant heating. Earlier this week, we added a panel radiator in the basement. The radiator was sized for 120° entering water temperature and turned out to be 3 finned layers, 10 feet long and weighing close to 200 lbs.(empty), 8280 BTU. It can be done, just a bit expensive.

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hvacsale

derate your baseboard for the EWT

more important is this:

When adding components to your potable water system, what will happen to the water when the system is not in use? If your plate exchanger and bronze circulator are outside of the normal flow of water through the water heater you must be careful. The water trapped in there while the zone is not in use can become a bacteria breeding ground and potentially spread through your potable water system.

Make sure that you have a pump timer of some sort to prevent stagnation in the bronze circ, heat exchanger and related potable piping. Read the spec's on whichever form of radiation you want to use and make sure to size it for your Entering Water Temperature. Be honest and subtract for the delta T in your exchanger also!

This is not the best way to provide heat because of the relative inefficiency of most water heaters and the additional components required, but if done properly at least you won't make your family sick by doing it.

Make sure to check your local codes as it may not be legal in your area.

Anthony Menafro

Hot water

Also make sure that the water heater has a cast iron burner for longer life, be sure that you use a vacuum breaker on the system and lead free solder with baseboard that has been flushed( Sterling Baseboard comes that way) of any impurities. You will also find that your water heater's thermostat dial will come off to allow you to lock it in at a higher temp, about 150 degrees farenheight, to get the most out of the heater. As said above, don't forget the mixing valve. You will have to use a spring loaded check valve to stop gravity circulation on the heat loop when the heater maintains temp. I've found that using a zone valve is a better way to stop the gravity circulation. I have done many of these type applications in towns such as Hoboken where you don't have the room for typical systems ans also change outs that were never done properly in the first place. Good luck.

Anthony Menafro