Hybrid Steam and Radiant Heat

scott inM.E.

I replaced the 50 year old timkin three years ago. It did work well beyond my oil dealers estimates, they like to sell new stuff.

When I got into this field 6 years ago I wanted to replace my existing steam unit. After doing many install's with the newer 3 pass boilers and radiant/panel heating I changed my idea's.

Now that I know better, for sure my old system was marginal due to the age, stack temp and the simple fact that the t-stat was in the living room with two rad's and only smaller rad's in the bath rm and bed room. I am sure when my house was built in 51' it was sized properly because as I pulled away carpets to remodel, I would find a hole were a rad. used to be.

adayton_2

Hybrid Steam/Radiant mix & match New Construction

This for the "just curious" thread. Why could a Hybrid system not be designed for NEW construction that would sport the new style low profile panel steam radiation (http://www.buderus.net/Default.aspx?tabid=36&cid=14&ctitle=multi-purpose) with Radiant floor and Radiant side panels AND DHW that would appproach 90% to 95% AFUE ratings (for total system)? BTU requirements to initially achieve steam are somewhat monsterous but once its task (steaming) is performed all the residual heat could be channeled to Radiant loops and DHW therefor not really wasting BTUs. This would give both the Horsepower needed in real cold climates (steam) and provide magnum COMFORT (Steam and radiant) for occupants. I should think that steam can be generated almost as efficiently from modern ModCon style boilers as can hot water for radiant systems. Any thoughts ??

Alfred

scott inM.E.

sounds like a good idea for radiant.......

if you had an existing steam system and added a radiant loop from the old boiler. Today's boilers used for radiant and panel radiator are cold start with 100-120deg. radiant loop temp's.

The prob with bringing in steam to the picture is comfort and fuel use. I had steam in my home and it was marginal for comfort and big on oil use. My Buderus is a fuel saver and I have warm friendly floor's.

Someone may design a boiler like you mention, but why bother. To me it's like asking for drum brakes, when 4 wheel disc brakes are the now. Improve on the present but remember the past.

Steamhead (in transit)

Scott, you must have had

a marginally-performing steam system.

Alfred, a well-performing steam system has two advantages over radiant: 1- it delivers heat more quickly (less mass to warm up) and 2- it won't freeze during an extended power or fuel failure. I agree radiant is tops for comfort, but a good radiator system isn't far behind.

If you take hot water from a steam boiler and run it thru a plate-type heat exchanger (steam boiler water can be pretty nasty) and mixed the temperature down, it could handle radiant (and domestic hot water) with ease.

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adayton_2

Steamhead Xchanger, Errr.. I Mean...

Radiant Xchanger running off the steamer pot of water. We are presently operating a radiant floor hePEX loop off of the DHW tankless coil in an Weil Mclain 572 Steam boiler.
The aquastat has always been set to 160*F for DHW production and this same pot of hot water feeds the radiant loop. I am certain a more modern efficient steamer boiler with modern control system including OAT setback features, water to water (for radiant pex) heat exchanger, 4 way automatic mixing valves, and TRVs on the steam radiation could be coupled with full radiant floor and wall panel heat system AND also provide DHW. After all it is just a lot of Hot Water delivered at BEST appropriate temperatures to the corresponding radiation. Just because on the way to generating steam for a portion of your heat (and comfort) needs you happen to generate a whole lot of (condensate) hot water....SO WHAT ??? lol,, route that Hot Water through pex and DHW so that all those BTUs are utilized and not wasted....With all the engineering genious that allows finnessing heat recovery (geothermal) from large ground masses or huge deep wells, we should be capable of designing a MODERN hybrid Steam/Radiant/DHW Heating system that is efficient and provides the BEST of BEST end user comfort that is afforded by both Steam AND Radiant solutions.

PS: The pex loop I reference has since been properly isolated from the DHW production. :-)...

Alfred

Steamhead (in transit)

How much load

is on that PEX loop? It might make sense to use a separate small hot-water boiler for the loop and DHW......

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