Plate exchnger for steam to radiant application

J Persons

I have a new customer who will be renovating and adding on to an old home. The renovation will require the removal of 30 feet or so of copper fin-tube steam baseboard radiation that was expertly installed and is very effective. The customers floor plan does not allow for perimeter radiation or contemproary panel radiators. The planned natural stone floors would be great for radiant heat but pose a question regarding a practical interface between the existing steam system and the low temp radiant floor requirements. Are there any thoughts out there on the use of a small brazed plate heat exchanger with steam trap and hot water mixing valve application for a steam to radiant floor application? My local supply house advises to simply do a heat exchanger off the existing DHW tank and leave the steam alone. I thrive on a challenge and can see additional future radiant zones that the oversized boiler could easily accomodate.

Floyd_7

Why not...

pull water from below the water line....add a pump,relay,t-stat, and a mixing valve and it seems you are good to go.
Why make a simple job difficult????

Floyd

Mad Dog

I agree with Uncle Floyd........................................

We pull them off steamers all the time. 2 ways to do it: no heat exchanger which is the cheapest way to go and I do not recommend because the steam condensate is muddy and will eventually clog the mixing valve and the circs - believe me I know. 2nd way. Use a flat plate HX (expensive) or a copper EVERHOT HX (not cheap , but affordable). If you do go with a flat plate, make sure you install a wye strainer before you enter the unit with steam condensate because the passages are very smal and will clog if you don't. The strainer should be flused once a season. In any case, you will need to install a simple bypass from the supply to the return off of the steam boiler to blend the supply water down to prevent flashing a steam. Good luck. Mad Dog

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GMcD

Plate exchanger for steam?

A regular old shell and tube heat exchanger for steam to hot water conversion would be the best choice. Works a lot better for steam service and condensate removal. Plate type exhangers are great for wetted surface applications (water to water/ fluid to fluid), but steam could be a challenge depending on plate spacing and pressures.

J Persons

Steam for radiant

Thanks guys. This is the type of input I was hoping for. I agree, why make a simple job difficult. I like the idea of pulling water off below the water line. This is far simpler and at a lower cost than using the plate exchanger or any other exchanger for that matter. I'm certain that it's time this old system got a good flushing out and this will give me a reason to replace some valves that are no longer useful due to age and deterioration of their seals. Due to the potential for future sludge I always include a "Y" strainer and isolation valves for servicing the pump and mixing valve. Thanks for your time to answer.
Jeff

DrV

Plate exchanger for steam to radiant application

Whenever pressure drop & fouling present simultaneous problems, check out a Gravity Film Heat Exchanger ("GFX") compared to conventional exchangers. Standard models have 1/2" Type-L copper coils wound on & 3" & 4" copper DWV tubes. All-copper construction eliminates differential expansion problems; double-wall-venting prevents cross-contamination. When operated in the falling-film mode (sealed or vented) these coil & tube exchangers have water-to-water heat transfer coefficients about 4 times that of a shell & tube exchanger having a tube I.D. close to 1/2". For radiant heating systems, the low pressure drop on a GFX's tube-side enables multi-loop operation with low power circulators. Some customers have applied them to commercial radiant applications requiring very high flow rates. Others have inserted their coils into geothermal loops to protect heat pump compressors from over-cooling by using wastewater heat to pre-heat return water. Some operated a GFX's tube flooded, with a lower heat transfer coefficient, to take advantage of their low pressure drop. Others use them to pre-cool FOG-laden water entering grease traps. A 3" or 4" GFX can pass sewage and debris found in hot wastewater heat. Their self-cleaning ability make them ideal for drain-heat recovery (DHR) applications. Hundreds of small GFX's are installed in series in main hot water recirc loops. Their coils provide heat for "instant" hot water recirc loops supplying fixtures in large Florida condos. They can be purchase On-line @ www.gfxtechnology.com.

Mad Dog

I would still use atleast an everhot HX

trust me J, I've pulled alot of zones off of a steam boiler. Regular baseboard is fine. However I have found out the hard way, that using steam condensate will cut down the mixing valves life, build up a film on the wall of the tubing and can be hard as hell to purge of air. At least, go with a simple Everhot HX and you won't be back on annoying callbacks like I have. Just trying to save you a headache. Mad Dog

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kevin coppinger_4

still yet...

another application to warm the floors would be electric radiant floors ( either low, 24V or hi,110V)...that way you don't have to deal with the HX, which if going hydronic I would use a very forgiving/non plugging type...kpc

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