BOSCH GREENSTAR COMBI 151 -PRO- vs GREENSTAR COMBI 151

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Ordie

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Looks like the HTP uft-80 can be installed with one CH system pump and no need for a boiler pump as long as primary/secondary piping is NOT installed (no closely spaced tees) , and use a check valve on the return line to the boiler.
Do I have to install the differential pressure bypass valve if I use a Taco Viridian VR1816 Circulator Pump as the CH system pump?
Also is there any difference between the HTP and Westinghouse brands other than the name? Any reason to choose one over the other?
 

Dana

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The boiler was designed for export by Kiturami, a first-tier Korean boiler & water heater manufacturer. HTP imports them into the US, and physically the Westinghouse versions are just a label-change, identical under the sheet metal, but the support networks are separate. If Westinghouse has more local resources, than HTP (not likely, in Maine), go with Westinghouse. HTP's headquarters are in MA, less than a day's drive from your house, and are reasonably well supported in most of New England.

There are minimum flow rates that have to be maintained (as with any boiler), so the pumping arrangement has to be reasonably well designed, and checked when commissioning the installation. In most systems the UFT series boilers can be a (more or less) drop-in replacement boiler for 1-pump cast-iron systems, but it's not always a napkin-math problem.
 

NY_Rob

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Looks like the HTP uft-80 can be installed with one CH system pump and no need for a boiler pump as long as primary/secondary piping is NOT installed (no closely spaced tees) , and use a check valve on the return line to the boiler.
Do I have to install the differential pressure bypass valve if I use a Taco Viridian VR1816 Circulator Pump as the CH system pump?
Also is there any difference between the HTP and Westinghouse brands other than the name? Any reason to choose one over the other?
As long as you can maintain the minimum required flow rate of 1GPM with just one of any of your zones open you don't need the differential pressure bypass valve.
If you go with a Grundfos Alpha2 for your CH pump- there's a handy LED display right on the end of the motor housing that gives you a fairly reasonable estimate of your instantaneous flow rate. Makes it much easier to figure what happening in your system. It happens to be an excellent pump too.
 

Dana

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Primary/secondary piping is usually only required with fire-tube boilers if the flow requirements on the radiation is quite high. The pumping head of fire tube heat exchangers is very low compared to water tube heat exchangers and can be operated over a wider range of flows than water tubes. Many water tube heat exchangers would require a monster-power pump to deliver 5 gpm+ flows (say, 5 zones @ 1gpm each) without primary/secondary plumbing, but most fire tube boilers would be fine with that. Lochinvar (for unspecified reasons) still insists on primary/secondary configurations with their fire tube boilers, but for most residential systems that's bordering on silly.
 
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