Hi folks, I usually contribute on the geo forum but had a question for boiler gurus.
Has anyone converted a 2 pipe steamer to hot water. What were the steps and pitfalls (been servicing/installing resi steam for close to 20 years and never had occasion to do this before)?
Also has anyone experimented with any form of water preheat system to cut operating time of oil steamer?
Thanks,
Joe

They like to leak....

I run my system 24 hours with TSP and leave with a strainer on the return. ModCons boiler exclusively for last 5 years.

What is optimum efficiency EWT for geo water to water systems you use?

I'm sure the old pipes do leak some. There's also the individual radiator traps that probably don't like to seal if you gut them.
I like the idea of an extended flush.
On geo, do you have a specific application question? Generally the higher the EWT, the higher the COP (efficiency) for heating, while the lower the EWT, the higher the EER for cooling. These numbers of course are oppositely affected by the radiation loop (or fan coil) EWT. So 50 degree ground water with 50 degree radiant loop water might give you a 6 COP for heating but 50* entering ground water with 100 * entering radiant loop water might be a 3.5 COP.
Hope that helps. If you have specific application questions, send me a private message.
J

Oh, forgot to ask, since most 2 pipe steamers are not in series, do they circulate without flow controls or are we looking at a repipe (of at least 1 side) anyway?
J

Joe

For any system I have worked on, to covert you would be talking about at least a 1 sided re-pipe if you were lucky.
I would be willing to bet the supplies would have to be re-worked a good deal as well given the fundamental differences in the piping hot water and steam.
I have never tried preheating the return or the boiler. Can't really see the point for steam.

I can't tell from here, but mine have been well balanced and work off a small circulator and outdoor reset. You have to make sure you have enough radiator once you derate them from 212F to 180F. This usually is no problem as the building are updated since first built.

I was thinking of water to water radiant floors usually 120°F and less.

You can approach 120* with conventional water to water of course, Climatemaster also has a new unit which supposedly can get to 140*. Trouble is (with all geo), as the ground gets colder LWT to process pipe will as well. If you were starting from sq 1 you would design your floor's loop density around 100* to avoid trouble. In a retro job, you could install geo water to water upstream of the old boiler so that you have aux. capability.
Regarding the preheating of water, elevating the return temp with a higher efficiency appliance came to mind.....but in thinking it through, most of the modulating high efficiency comes from lower water temps so much for redisigning the wheel.
There's so few steamers left around here I'll only see a couple a year. Do they have resi economizers for them?
J

The old boiler may be way too big to provide aux heat. Depending on the fuel. Unless the aux was say about 20% of the load.
Those old guys don't modulate like the new ones. I have worked with some modulating oil burners but they were pretty big and expensive, not really sized for anything residential.
Staging the Geo and a boiler is no big deal. You would need a buffer tank and some controls. Outdoor reset is a must.

Badger
I meant to ask what size systems and what type of return have you been able to retro without to much re-piping?

Typical three story Victorians and smaller. If I anticipate a problem with balance I run PEX home run to each and back to a radiant floor manifold with zone actuators or add a TRV at each rad.

Most have supplies and returns 3" or bigger and flow is not a problem but as you suggest, balancing can be. To be safe a TRV or a valve at each rad minimum, full time pump sized to the boiler flow and head and outdoor reset.

I am in the Philadelphia area.
Here most of the big turn of the century homes were steam.
Most I have seen, the returns were all piped with 1/2-3/4" dropping to risers of 1" then connected to a larger loop,1-2", in the basement.
Many times this was circling the basement at floor level.
Then returning to a boiler trap or pump.
I has seen several retro fits. Most were pretty good but a few, It was amazing the owner got any heat at all.
Someone would just cut the old boiler trap out, remove the old header divide the main loop and install 2 pumps to the mains.
They would ignore the inadequate return flow.

I appreciate your thoughts folks.
J