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-   -   Radiant heat/boiler question (http://www.diychatroom.com/f17/radiant-heat-boiler-question-54483/)

gbwillner 10-05-2009 03:47 PM

Radiant heat/boiler question
 
Hello all,
I have a large boiler in my basement that feeds 12 radiators in the first and second floors of my house. I don't know the BTUs off the top of my head but the unit is rather large (about 4' x 3' x 2') and is from 1993. The radiators run in a parallel ciruit. I am in the process of remodeling the basement and want to get rid of those darn pipes that crawl all around the periphery and are huge. I was wondering if it would be possible to use the current boiler to run in-floor radiant heat for the first floor (since I have just now exposed the first floor joists) and keep the radiators on the second floor.
I was also wondering if I could replace all those giant pipes with PEX that I could hide in soffits, and not bang my head on.

I was about to purchase Modern Hydronic Heating for Residential and light commercial buildings (by Siegenthaler) to help me design this set-up, but want to know if it is feasible first.

Thanks!!!

Viper16 10-05-2009 04:05 PM

is this a water boiler, or a steam boiler? I am assuming water since you want to use pex. are all the valves near the radiators on modulation controls?

we would really need to know the size of the boiler to give a decent estimate.

gbwillner 10-05-2009 04:21 PM

Quote:

Originally Posted by Viper16 (Post 336689)
is this a water boiler, or a steam boiler? I am assuming water since you want to use pex. are all the valves near the radiators on modulation controls?

we would really need to know the size of the boiler to give a decent estimate.


Thanks for the response...
it is a water boiler. I will find out the size tonight. Since I have no clue what you mean by modulation controls, I will say no.

Viper16 10-05-2009 04:27 PM

is there thermostatic valves (a temperature controller with a knob to adjust the desired temperature) that control the water through the radiators? surely they are not blowing through full flow through each radiator are they?

Also what is the average temp in the winter for you? is the insulation good? it takes more btu's to warm a house that is poorly insulated.

gbwillner 10-05-2009 04:30 PM

Quote:

Originally Posted by Viper16 (Post 336702)
is there thermostatic valves (a temperature controller with a knob to adjust the desired temperature) that control the water through the radiators? surely they are not blowing through full flow through each radiator are they?

Also what is the average temp in the winter for you? is the insulation good? it takes more btu's to warm a house that is poorly insulated.

There is a simple valve to control the flow of hot water. Most radiators are original from 1909, although a few were replaced in in th 1940s.
I am in Saint Louis, and the average cold temp in the winter is probably 20 degrees or so. I live in a 2-story solid masonry home with no attic. There is probably no insulation in the walls other than the brick. Most windows have been replaced with energy efficient ones, and I don't have too many to start with.

Kool Rod 10-05-2009 06:02 PM

Plan for the Future.
 
It sounds like a steam system (big pipes) that was converted over to gravity hot water. You have a good approach in that you're reading up on hydronic systems. Before doing anything I'd spend a lot of time reading. Siegenthaler is good and you might also want to get "Pumping Away" by Dan Holohan. (www.heatinghelp.com)

I'd put together an overall plan with the idea that you're going to remove and modernize your whole heating system overtime and then do it section by section. If you come up with a good overall design first this will prevent you from having to redo things later. In the end you'll probably want to switch to a modcon boiler which would save a lot on fuel. I'd also look into TRVs (Danfoss) to regulate each individual radiator temperature.

Hydronics has come a long way in the last few years with computer modulation and outdoor resets etc. You might want to look on the different boiler manufacturers sites as some of them give lot of design info in their Installation and Operating Manuals (I & O) Here are some manufacturer names - Smith, Weil-McLain, Dunkirk, Peerless, Lochinvar, Viessmann Most companies offer both standard hot water boilers and modcons. Doing your "homework" now will save you a bundle in the long run.

Edit: Forgot to mention Slantfin as a boiler manufacturer. They have a lot of good technical info. as I remember. I 've a Peerless boiler in my brother's home and have been quite impressed with it.

Viper16 10-05-2009 06:39 PM

Too add to the boiler manufaturers list you might want to take a look at sterling radiator for fintube floor heaters....to replace your older units. these are very efficient units. I am a rep/distro. for Peerless and Sterling radiator. You would need to know what the delta temperature would be for each room and the required BTU/H req's, then we would add a few for pipe heat loss, and then size your boiler with that, then of course your expansion tank might need resized.

Depending on the current efficiency of your unit, you may save money in the long run, by going with a new system...the payback could be 5-10 years or sooner.

tk03 10-05-2009 08:40 PM

I would not change the radiation for efficiency reasons. You probably have much more radiation then you need which is a plus. Pipes can be moved though.
Have a heat loss done so you know what each rooms heat loss is and determine if there is enough unobstructed floor. It also allows you to figure water temp for outdoor reset controls. If you do not do underfloor radiant keep those old rads. Lower heat loss due to less air currents and more comfort.
For more heat loss info see link
http://www.comfort-calc.net/faq.html

gbwillner 10-06-2009 10:30 AM

Thanks everyone for your help so far.

The boiler I have is 140,000 BTU/hr. All floors are hardwood oak and each floor is about 900-950 sq ft.

Can I do both radiant heat on the first floor and radiators on the second?


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