some fitting upgrades for old cast iron rad hydronic system?

jeffro83

Hey there.  A few questions for anyone out there willing to lend some advice; I apologize in advance for the length of this post!



I've got a rental house in Ontario, where the outside temps have already been colder than -30 Celsius this year and the heating system has been giving my tenants some issues over the past little while, so I'm hoping to help them out as best I can from many provinces away.  An attempt at sending a couple of the local plumbers/HVAC guys over there hasn't really fixed anything, as everything was working fine once they got there, so I'm hoping for a bit more insight here.



The biggest issue they're having is that 2 or 3 of the rads are rarely heating up at all.  These rads are all on the

same wall of the house (front side, or opposite side of where the boiler's installed; not sure if that matters) and they're on both the main and 2nd floors.  The rest of the rads in the house are working fine.  I've never taken a close look at the different routes that the heat is pumped up to, but I'd imagine these are all on either the last loop, or there's something blocking them from working properly (dirt/crap/air lock).



The boiler room is apparently quite hot as of last night, and it sounds like the safety relief valve on the boiler manifold has been relieving itself more than it ever should be.  Pressure seems to always be climbing to nearly 30psi, when it lets go.  Upstairs, the thermostat has a call for heat of 74 F, yet the actual temperature still reads 66 F or so and doesn't get any warmer than that (maybe 2 or 3 days now?).  According to my father who stopped in to see if he could fix anything, the Schrader valve on the expansion tank would leak a dark brown bit of goo if he tried opening the valve for a quick second.  I don't know if that's sludge in the system or the diaphragm in the expansion tank disintegrating, but he said the tank sounds like it's full of water (diaphragm not diaphragm'ing).



The boiler (a 4yr old Buderus GB-142), has pretty much been running flawlessly over the past few years, with the exception of tweaking it at the start to operate smoothly.  It is heating a number of ancient cast iron rads from the basement, going up 3 stories.  Two rads up in the top loft, four rads on each exterior wall of the 2nd floor, and four rads on the main floor.  Pretty sure my expansion tank (Extrol 30) has kicked the bucket, so I'm ordering a new one (an Extrol 60, as I think my boiler is sized between the 2 suggested expansion tank capacities, so I figure a larger one couldn't hurt).





I'm also curious about a couple other things though.



I have no in-line dirt/particulate filter in the system, and haven't since I bought the house, but the more I learn about these systems, the more I think it's foolish that there was never one installed when I replaced the old boiler 4 years ago.  I've drained the entire system a couple times since then, mostly to get some lines changed around, and added an inhibitor solution both times.  Apart from that, it's been a mostly closed system (aside from letting city water into the system on an automatic fill valve).



I have read a lot lately about this Fernox TF1 filter system that seems to be big in Europe, but not at all across the pond. 



<a href="http://www.fernox.us/equipment/filters/tf1+total+filter">http://www.fernox.us/equipment/filters/tf1+total+filter</a>



Does anyone have any experience with these?  Any comparisons between the Fernox and something like a SpiroTrap dirt separator?  The Fernox looks like it can handle a lot more crud if need be than the SpiroTrap.



I also don't believe there's ever been an air eliminator anywhere in the system.  It's always operated fairly well, and I was quite a newbie when it came to hydronic heating when I bought the house.  The only spots in the system to eliminate air automatically, as far as I can remember, are in the top loft, where I have a Watts automatic air vent on each of the 2 rads up there.



I'm assuming installing something like a SpiroVent on the supply side of the boiler would be the norm?





Anyway, thanks to anyone that made it through this series of questions.  If you have any advice, I'm all ears.

Steamfitter66

Start with a bad expansion tank.

Thats whats causing your relief to go off, It will need to be flushed and an inhibitor put in the system water. It needs to be serviced by someone competent and experienced with gb142.

A Spirotrap or a filter may be needed depending on how much and what type of sediment you have.