You are here:

Heating, Air Conditioning, Fridge, HVAC/proper temperature for circualting hot water baseboard heat


QUESTION: What is the proper temperature for water in a recirculating hot water baseboard heating system? My mother recently had the pump replaced and has had problems with the heat ever since. Today the technician from her utility company bled the system and increased the water temp from 180* to 190*. Her system uses the same tank for domestic hot water and heating. Her hot water at the tap was already quite hot. Now it will be hotter.


The baseboard probably needs 180F in very cold weather.

Your Mom is way behind the times, both in terms of personnel safety and energy use: A tempering valve has been required for decades to maintain domestic hot water temperature within safe levels; using a boiler to generate domestic hot water in mild (when the boiler temperature could otherwise be reduced)and warm weather (when the boiler could otherwise be turned off) has been archaic since the 70's Energy Crunch.

She needs a separate hot water heater (gas preferred, or electric if there's no gas - oil is the worst form of energy known to man). Then she can have an "Outdoor Reset Control" installed (Honeywell T475A with a 1:1 ratio set for 100F or so has been my preference for four decades or so - be sure to provide a "well" so the bulb senses water temperature, rather than strapping the bulb onto the pipe surface) to adjust boiler temperature based on outdoor temperature. Finally, rearrange the control wiring so the boiler only fires when the thermostat calls for heat.

She'll save a bunch of money, and you won't have to worry about her being scalded!


---------- FOLLOW-UP ----------

QUESTION: No question it is outdated. Hers is the only house in the neighborhood with the original system. Believe it or not it has lasted since the home was built in 1960. There is no space for a separate water heater


No space??? I can't believe that: A single person could easily get by on a small electric water heater set on a shelf, installed in a closet or whatever.

If the boiler's cast iron, it's just getting started at 54 years old!

Alternatively, replace the boiler and gain beaucoup floor space for a water heater.


Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts


Fred Weldin


I can't help you if your whatsis won't work, people (Especially if it's a refrigerator); I have no experience with appliances, and I haven't been involved with H&AC service and repair since March 08, 1996 (Thank the Lord); I always send a "standard" reply to appliance questions and H&AC "Service and Repair" questions (about 20 a month), so if you want to know why your whatsis isn't working like it used to, ask someone else. A lot of my answers arenít read by the questioners; in that event, I always send reminders to read the answers for a month or more (the word "idiots" comes to mind - actually there's another more appropriate word, but discretion prevents its use here). If you have questions about how big a unit you need, if one room's warmer than the others, if you want an opinion oas to scope of work on bids received, etc. just ask. Do visit, there's a lot of good information on sizing, ductwork, efficiency, as well as some techniques accomplished DIY-ers can use to troubleshoot and improve their H&AC. Finally, I want to thank all of the kind, serious people whom I meet here: I enjoy working with you. My wife says I'm "snarky" from time to time; as for you others, please use your imagination as to the responses swirling on the snarky side of my brain when I read your questions.


53 years in the business. See


B of ME U of D 1965, numerous classes, seminars and a lot of "Hands On" learning since.

©2017 All rights reserved.