reset curves linear, radiator output nonlinear?

R. Kalia

cast iron? what's that?

Cast iron? In 2004?

Seriously, I have learned a lot by reading posts here, and while I want to save money, a non-condensing boiler is not an option.

S Ebels

SOooooooo......

I take it that you are using a condensing boiler? Which one?

R. Kalia

planning...

Planning to get an MZ if I can swing it.

I have to find someone who knows the MZ but also the Tekmar 370. I haven't gotten a quote yet. It'll probably be more than I can afford. I'm not even getting a quote for a Viessmann, I know that if I need to ask the price, I can't afford it.

Kevin McAfee

Time based heater control

In regards to this discussion, I was thinking that the "ideal" solution is balancing heat loss with supplied heat. I recall seeing a post in the past several months that spoke of a controller that used the frequecy of heat calls to to set the boiler temperature ( or water temperature) to maximize circultaion. It did this without an outdoor sensor I believe. Instead it used a the frequency of heat calls as the "sensor". HAs anyon used this controller and would it eliminate the need for outdoor reset?

Thanks for your thoughts.

S Ebels

A couple things

1. Check with your local code officials on being able to use the MZ. At present it is not an {H} rated heating appliance. Because of this, you can't install it for space heating in some states. (Michigan being one)Code people in Lansing are a little backward here.

2. I might be wrong but I don't think the MZ is a condensing boiler.

3. Get a quote on the Viessmann and remember that the control on that boiler will do all the basics for DHW, setback, reset, DHW timing, running a mix valve etc. right out of the box. Saves you the price of the Tekmar and it's designed from the ground up as an integral part of the boiler. Not an add on or something you have to "make work". As the good Germans say, "Ve ploog und Verk".

R. Kalia

Thanks for the comments!

> 2. I might be wrong but I don't think the MZ is a

> condensing boiler.


You are wrong. Sorry.

R. Kalia

I read their web page

http://www.exqheat.com/pages/707613/index.htm

It's a pretty primitive method. It doesn't do anything that outdoor temperature feedback or indoor temperature feedback can't do better. It monitors the duration of heat calls and adjusts the water temperature up or down until the thermostat is calling for heat I think 2/3 of the time. It doesn't aim for close to 100% operation because it might overdo it and then the house would get cold. So you don't get constant circulation, and the response to changes in heat load is slow.