GB145 and Cast Iron Radiators

charlie from mass

I was sure I had read it on the first GB I installed a few years back but it does not say it in the current manual. I would still be concerned about the crud coming around from the rads but not the cold water as the manifolds would take care of that problem. I would take it system by system though. On a former gravity job with lots of iron piping I would take extra caution and I have not had much luck with cleaners on these systems, seems to be lots of nooks and crannies for sludge to hide. I say clean them treat them and use a good dirt seperator of your choice. Seems the rad systems are prime for low water temp of these boilers.

DennisF

GB145 and Cast Iron Radiators

With oil prices as they are,and my old Utica boiler being over 30 years old, I'd like to install a new boiler. I've been looking at the Buderus GB142/45 but a guy told me the other day that I can't use it with my old cast iron radiators. Something about loosing the efficiency I should get on the Buderus. I've used the GB142 on other installs with good resilts and like a lot of thing abut it. What's up witht he conflic with cast iron radiators? Thanks

Brad White_200

No reason not to that I can think of

Maybe that guy is coveting your CI rads? I would watch him

Cast iron radiators are ideal heat emitters, besides that, you already own them. They work at any water temperature from just above room temperature to whatever temperature you need.

If you have an older house with radiators sized for the original heat loss and since then the house has new windows, insulation, air sealing and so-on, you have a surplus of radiator capacity. That means your heat loss can be absorbed with a lower water temperature for sure.

Remember though to start with an accurate heat loss. Do NOT use your old name-plate data, firing rate, what-have-you. The boiler matches the heat loss as closely as you can.

The actual water temperature will be determined as you operated it. You may find that you will be condensing (ie: most efficient) in even the coldest weather.

You will save money to the extent that you will be using much less fuel.

ScottMP

All that cold water

rushing back to the GB... thats baby will be condensing like abroken water bubbler in July.

I LOVE the GB with big old cast iron radiators, don't listen to that the guy.

Scott

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[Deleted User]

perfect

That is a perfect hydronic setup. zi would recommend using a low loss header or a Wye strainer on the return to help protect the heat exchanger from mineral buildup.

scott markle_2

spirotherm dirt trap- won't plug up like wye strainer could.

Charlie from wmass

Check the install manual.

You need a heat exchanger with the aluminum block boilers or the iron in solutin can clog the water passages. Other wise no issues. This goes for lots of iron in the manifolds or loops also. Also electrolosis

Charlie from wmass

Check the install manual.

You need a heat exchanger with the aluminum block boilers or the iron in solution can clog the water passages. Other wise no issues. This goes for lots of iron in the manifolds or loops also. Also electrolosis. The high mass of the system and hopefully over sized rads should make for lower water temps for heating the house, which would be to the benefit of the Buderus. I could not find it in the current manuel maybe the WeilMcLain I am thinking of but I would say that the sludge and other goodies is the only thing to worry about. Maybe a good dirt seperator would also help. If all else fails check with buderus direct they have good people there from my experiance with them.

scott markle_2

Charlie does the manual say that an exchanger is necessary?

Good water cut with rhomar inhibitor , I bet you would be fine. but check with buderus.