Which size to choose?

The MST396 only

i would also recommend installing it using a drop header. As per the manufacturers specs. The only thing I would do, if possible to augment Burnham's specs as to the near boiler piping is this:

1. The 2 risers exiting the boiler, get them as high up as possible. not just the 24" to the bottom of the swing joint.

2. The main boiler header. I would increase the size to 2 1/2" to 3"

(This piping will assist with slowing down the steam & help in keeping it as dry as possible.)

3. The hartford loop pipe at 1 1/2"

4. The return line. I would not use any size less than 1 1/2"

5. Make sure your installer uses an automatic water feeder with a manual bypass.

(I recommend a VXT-120 because it has the meter display)

6. Make sure the installer use black pipe and Cast iron fittings (CI) for the piping- NOT COPPER

(I really shouldn't have to say this, but given how many steamers we re-install every year, because some people either do not how to do it properly or want to take a short cut, for time purposes, I mention it.)

7. Have the system completely flushed before installing the new unit.

(We do, and I must tell you, around here, almost no one else does it. Let alone even knows it needs to be done. It may cost a little extra labor but the benefits far out way the cost)

8. Main vents ok? As a matter of course, we replace the main vents on every install. (when equipped) Some would argue, that it isn't always necessary, however, when a client is already spending thousands, why not. It's not going to hurt.



Remember, it is the details of the job and the extra little things, like i wrote that will make the install go better and the system perform correctly and most importantly, efficient. saving you $$ in the long run.



btw- where are you located?



And good luck, the MST is a fine unit, works very well, when installed properly

Great tips...

These are great tips for a new instal. Could you share how to flush out a system? I'm a homeowner of a two-pip Trane Vaporvacuum system that will soon be getting new boilers. I'd like to do this myself to ensure it gets done.and hadn't considered this  before.I will be re-piping the wet return.