Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
Variable speed heating zone circulators:
This article describes brands & models of forced hot water heating system circulator pumps whose motor speed or circulating speed can be set to varying rates.
We describe both older obsolete variable speed circulator pumps and modern currently-available models including manufacturer brand, model, and circulator pump sources.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
Variable speed heating zone circulators provide an additional level of heating zone control and can be used to solve heating problems amenable to either an increase in circulating water speed (get more heat in a zone) or a decrease in heating zone circulator speed (less heat or continuous, more even heat).
Older Variable Speed Heating Circulator Pumps
At left is a Bell & Gossett UpStart hot water heating zone circulator pump produced - a B&G product no longer distributed. This circulator pump included a variable-speed circulator motor (see that gold knob on the electrical box atop the motor?).
This hot water heating zone circulator used a four-speed motor whose output rate could be set by the consumer or heating service technician.
By changing the circulator motor speed on this pump or on the next model shown below, we could slow or speed the flow rate of hot water through the zone managed by this circulator. The result: this control provided another way to balance heat flow among multiple zones (and circulators) in a building.
This circulator, the Bell & Gossett SLC-25 Upstart Circulator was sold during the 1980's and is not currently available. But B&G offered similar replacements (such as the NRF-22).
At below is a newer but also obsolete product, the B&G NRF-VS variable speed circulator is shown.
Currently-Available Variable-Speed Heating Circulator Pumps & Controls: Taco BumbleBee & Grundfos Alpha Series & MixiMiser™
Other variable speed circulators include the Taco BumbleBee High-Efficiency Variable-Speed Circulator HEC-2 and Variable speed circulators from Grundfos.
Quoting from the company's product literature:
The Taco Bumble Bee (model HEC-2) represents the very latest in variable speed wet rotor circulator technology. Its high efficiency ECM motor uses up to 85% less electricity than a standard circulator, and its out-of-the-box settings and 360 ̊ swivel flange makes it a breeze to install. Most importantly, the Bumble Bee’s Delta-T variable speed technology maximizes the overall efficiency of your heating system. - Taco Catalog q#100-101 retrieved 1/24/2014 [on file] see References at the end of this article
Alpha Series pumps by Grundfos also provide variable speed hydronic heating water circulation control. Quoting [with minor adaptations] from product literature from Grundfos, including the UPS15-58FC and the Grundfos Alpha series.
Continue reading at CIRCULATOR PUMPS & RELAYS or select a topic from the More Reading links shown below.
Suggested citation for this web page
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
No FAQs have been posted for this page. Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
HTML Comment Box is loading comments...
Technical Reviewers & References