Pumps

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John Molyneux

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A contractor with whom I've discussed my new boiler install is recommending 3 Grundfos circulator pumps. This confused me because the current boiler operates off one internal pump and supplies 2 heating zones and an indirect DHW tank via zone valves.

The proposed system is a TT-60 that will feed into one heating zone (that has plenty of cast iron radiator capacity) + a Smart30 indirect.

Would someone be kind enough to give me a quick primer on pumps -- quality and quantity -- for this type of application?

They're also recommending a magnetic filter since we're tying into a 75-year-old cast iron system. Any thoughts on that?

Thanks in advance!
 

Tom Sawyer

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You need at least one other besides the boiler pump and it should be a Taco Veridian Delta T pump feeding two Taco zone Sentry valves. Three grundfos pumps are ok but a waste of electricity and the delta T pumps will match to the radiators more efficiently.
 

John Molyneux

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You need at least one other besides the boiler pump and it should be a Taco Veridian Delta T pump feeding two Taco zone Sentry valves. Three grundfos pumps are ok but a waste of electricity and the delta T pumps will match to the radiators more efficiently.
Thanks Tom: That pump looks pretty cool. I already have one of the Sentry Zone valves that was used to replace an older model that died last year.

But I'm still confused why I need at least two pumps. One for the supply and one for the return? I'm just curious more than anything.

I think the TT-110 is the only model in that line that has an internal circulator. It doesn't look like the TT-60 has an internal pump.

Any thoughts from anyone on the need for a magnetic or other type of filter?
 

BadgerBoilerMN

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We install condensing boilers in old houses with cast iron radiation every week here in Minneapolis. We even use the Triangle TT on occasion.

One pump, that' it. One.

First, the radiation was designed for gravity flow. No pump.

Second, the boiler will suffer a 45F delta T.

Third, the boiler only requires a minimum of 3 gpm.

The current system, with old boiler intact, should be cleaned with Fernox, flushed and treated. You may use a Fernox power flushing machine with a magnetic filter if you find debris in the flow but a permanent magnet will serve no purpose in most radiator systems.

A simple three speed Grundfos 1558 will suffice with a zone valve for each zone and priority to the DHW.

We sometimes opt to drive the indirect with it's own pump using the TT internal relay when zones are few as it may save some time and money.

In no stretch of the imagination will you need three pumps. This is simply old-school.
 

John Molyneux

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We install condensing boilers in old houses with cast iron radiation every week here in Minneapolis. We even use the Triangle TT on occasion.

One pump, that' it. One.

First, the radiation was designed for gravity flow. No pump.

Second, the boiler will suffer a 45F delta T.

Third, the boiler only requires a minimum of 3 gpm.

The current system, with old boiler intact, should be cleaned with Fernox, flushed and treated. You may use a Fernox power flushing machine with a magnetic filter if you find debris in the flow but a permanent magnet will serve no purpose in most radiator systems.

A simple three speed Grundfos 1558 will suffice with a zone valve for each zone and priority to the DHW.

We sometimes opt to drive the indirect with it's own pump using the TT internal relay when zones are few as it may save some time and money.

In no stretch of the imagination will you need three pumps. This is simply old-school.

Thanks Badger.
 
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U need 2 pumps. One for the system (zone valves) powered from the CH connection & one for the Smart30 Indirect powered from the DHW connection.

Both pumps need flow check valves on their outputs as they will be pumping away from each other.

Only one or the other will ever be powered, but the 2 flow checks are needed to prevent backflow through the other pump.

You don't need 3 pumps for a Primary/Secondary setup as the boiler has very low internal flow restriction.

This is shown in Fig8 on page 20 of installation manual.

The Solo60 don't have the internal pump like the 110 has.
 
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