Hey guys. I have a radian heat Idea. I want to ask all of you experts what you think about the following.
I'm going to build a one story building with basement in Canada. Heat Loss Calculation shows for the basement around 40,000 BTU. 5 loops 250' each, 1/2 pex. The first floor around 45,000 BTU with 3 zones, each one is two loops 250' each. I'll use a regular gas boiler and indirect water heater. I have an idea ! What if I will use the same heat exchanger to heat domestic water and radian heating? I'm going to try to connect the heating line into the heat exchanger's line between the boiler and water heater. Is this going to work? I understand that I have to keep the water in the water heater around 160F to prevent the condensations in the boiler return. After the boiler heats the water heater and pomp and the solenoid valve shuts down, the heating can use the same heat exchanger from the water heater using the water heater like a buffer. Now I have a couple of stupid questions.

1. Is the heat exchanger powerful enough for use in such system? (total load 85,000 BTU)
2. If the boiler begins working, the temperature before mixing valves will quickly increase up to 185F. Will the mixing valves hold selected (say 110F) temperature for the radiant heat without a huge jump in temperature?

3. For the basement I'll use one zone with one pump. 1st floor will have 3 zones controlled trough the zone valves loaded onto one pump. If two zone valves will be deactivated (turned off by the thermostats), and one zone will be left to work how will it effect the pump? Is the flow into this zone increase badly for the pump? What might happen? Noise? Overloaded pump?

This system is good for the following reasons (if it works)
We are saving.

1. avoid using additional heat exchanger.
2. avoid using additional pump for this heat exchanger. All such system (four zones and water heater) only 3 pumps will be used.
3. Because boiler is controlled by the integrated thermostat inside the water heater, we don't' need any additional controllers or relays or thermostats.
4. Domestic water will also be separated from the heating system.5. We save over 1000 bucks.

Please use as much constructive criticism to help me as possible. THANKS!

HAPPY NEW YEAR!!!

Gary get ready for some bullets and swords . Hey Bill Clinton are you out there? As we said it was too quiet and peaceful so now here is another oportunity for "discution" .
Actualy We have discused this subject in detail and have had "SPIRITED" talks but it was all good. Through this great give and take there was a statement written up on the protection of "open system or closed system" . If I remember the code in Canada is slightly different than the US but does allow this to be done.If you are to do it though you should read both sides of the argument and then decide if this instalation is for you.
If you keep the water temp up and flush the heating side from time to time and circlate the water from stagnation you have done much to play it safe but there are those who would say it is still not "wise".
I think that in your situation you should deside what real advantage this will give you.Sometimes a "open system" could seem a good idea because of equipment or location issues but you will have a full boiler. Now you have choices and posibilitys with Variable speed pumping or mixing or multiple temperatures.Your better choices would start from the boiler.

I don't see any purpose in what you propose to do. Either that, or I don't understand your proposal.

You mention "I'm going to try to connect the heating line into the heat exchanger's line between the boiler and water heater". That isn't really a clear statement. I assume, from additional comments, that you are going to connect into the potable water side of the exchanger. Why? There is no benefit and a host of disadvantages, including potability issues, and the issue of connecting the heat distribution components to an unlimited supply of water at a relatively high pressure. Say nothing about living in the tundra and not having any glycol protection in the radiant loop.

Why wouldn't you simply tap into the loop between the boiler and the heat exchanger and use a tempering valve to reduce the supply water temperature. That's about the most common way of accomplishing what you need to do.

There are, of course, a lot of other alternatives that make more sense to me.

good luck,

tom