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circulation

Print circulation is the average number of copies of a publication. Number of copies of a nonperiodical publication such as a book called usually print run. Circulation is not always the same as copies sold, often called paid circulation, since some issues are distributed without cost to the reader. Readership figures are usually higher than circulation figures because of the assumption that a typical copy is read by more than one person.
Print circulation is one of the principal factors used to set advertising rates. In many countries, circulations are audited by independent bodies such as the Audit Bureau of Circulations to assure advertisers that a given newspaper does reach the number of people claimed by the publisher. There are international open access directories such as Mondo Times, but these generally rely on numbers reported by newspapers themselves.
In many developed countries, print circulation is falling due to social and technological changes such as the availability of news on the internet. On the other hand, in some developing countries circulation is increasing as these factors are more than cancelled out by rising incomes, population, and literacy.

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  1. R

    Reverse Circulation - Sense Check

    Hi everyone, I'm a (somewhat, I hope...) competent DIYer and just want to get some advice if my suspicion on a problem we're having is correct. We had a Megaflo and boiler professionally installed as part of a renovation a couple of years ago. I will add all of the pipework was done by this...
  2. H

    Requirement Circulation pump for the hot water secondary Return

    Silly question (and might already been asked 100rds of time) - I am specifying a circulation pump for the hot water secondary (circulation) return to reduce the wait for hot water. HW is coming from unvented cylinder with a secondary return connection. The secondary return is almost straight...
  3. B

    Possible reverse circulation

    Hi all, we've recently moved into a property and believe there is some kind of backflow in the heating system. (I should say I am a DIYer, and not a great one). When we have our hot water on, the rads get hot over time. I've had floorboards up to see if there is a non-return-valve somewhere...
  4. M

    Reverse circulation Solid Fuel

    I have a Rayburn running my CH and HW, when the boiler is lit, the gravity flow works as it should rises to the cylinder and drops back to the boiler...when the cylinder is hot enough the CH pump comes on and this is where it goes wrong. The pump seems to be pushing the cold radiator water up...
  5. elczkc

    Reverse circulation?

    Just had extension built with 1 new rad and 1 plumbed in towel rail. Since this was connected I have had problems with radiators getting hot with only the HW on. Have checked the motorised TWV and this appears to be OK. I have tested for reverse circulation in an existing upstairs radiator and...
  6. E

    Central Heating circulation issue

    Hello i recently converted heating system from old stove to grand vortex b house 90 , boiler runs and works fine . How ever i have issue with water circulation have installed new pump but for some reason water don't circulate at all . what are the possible cause ? i have pump installed on return...
    • egizz983
    • Thread
    • central central heating circulation heating issue
    • Replies: 54
    • Forum: Central Heating Forum
  7. T

    Is my circulation pump failing or my boiler control?

    I have a Viessmann Vitogas 100, installed about 17 years ago by a previous homeowner. It also is the boiler for hot water, so it runs all summer in hot water only mode. I’ve turned the heating component back on, but it’s not working properly. It would appear the circulation pump stops working...
    • thebigsleep
    • Thread
    • boiler circulation circulation pump control pump
    • Replies: 3
    • Forum: Central Heating Forum
  8. N

    Circulation Pump Question

    As mentioned in my 'System Drain' thread the house has been extended in 1986. In recent years I felt the circulation was not as good as it should be . I have previously replaced a section of pipe when we had blockage at point where cold feed joins together with clean and drain, refill+...
  9. J

    URGENT water circulation pump too hot

    Hi all, I just found the red pump (attached photos) is very hot, is this all right? Or something wrong? The radiators are very hot, the red pump which is workman 25-60 hot/cold water circulation pump is very hot too. My system is unvented cylinder+heat only boiler. Is this normal that the...
  10. A

    Why is my new circulation pump twice as loud as previous model?

    Hi all, Let me start by saying, my heating works fine. I only know the basics of a system, and this may well be just me and my sensitive hearing... I have been in my property for 5 years. I had a Wilo circulation pump, which purred wonderfully. I never took a photo of it as a reference, but it...
    • Adam_and_the_boiler
    • Thread
    • circulation circulation pump grundfos heating model previous pump twice wilo
    • Replies: 10
    • Forum: Central Heating Forum
  11. bucket bearer

    Can a pressurized open loop use a smaller circulation pump?

    Grundfos advertises their Alpha 1 & 2 pumps (I'm not sure if they just call both versions Alpha now); that it will replace 30 other pump models. I've been using a UP15-29SU for many years. I'm using it to circulate water for our domestic hot water that uses a 3/4" copper pipe which goes down...
  12. bucket bearer

    Does a pressurized open loop need a smaller circulation pump?

    Grundfos advertises their Alpha 1 & 2 pumps (I'm not sure if they just call both versions Alpha now); that it will replace 30 other pump models. I've been using a UP15-29SU for many years. I'm using it to circulate water for our domestic hot water that uses a 3/4" copper pipe which goes down...
  13. J

    One pipe circulation

    Hi just wondering does a presurised hot cylinder outlet have to be @470mm on the horizontal like with a open vented cylinder??
  14. S

    DHW Secondary Circulation Control Strategy

    Hi Everyone, thought I'd pick your brains on some ideas I have for controlling a DHW secondary circulation pump circuit that I'll be installing as part of a new build. The DHW supply will consist of an Air-Water Heat Pump source linked to an unvented cylinder (at mains pressure). Never had the...
  15. B

    No room to fit circulation pump, any suggestions on what to do?

    I am replacing an air source heat pump. The current hot water tank, valves etc are all staying so should be a fairly straight forwards procedure, however the new heat pump doesn't have an internal water pump or flow switch which both need fitting to the plumbing system. Surely the water pump...
  16. D

    positioning of secondary circulation pump

    Very last rad on heating circuit is a vertical mounted iguana circo rad, which is 1.8m high. The rad is not getting sufficient water flow even after balancing all other rads. Placement of a secondary circulation pump will alleviate this issue but the question is where best to locate it. Near the...
  17. O

    Circulation pump bore diameter

    Can anyone tell me what impact running a circulation pump with a larger diameter bore would have? Currently running an old grundfos 15-6 on 22mm with 1 1/2 threads but looking at a lowara ecocirc 25-6.
  18. gcleve

    Set Worcester combi boiler to circulate without heat.

    Hi there - I have a Worcester Greenstar 25Si combi boiler running our heating rads. I've recently added a small tank with a heating element powerd by solar into the rads circuit. It's producing good heat, but I need a circulation pump to be on to move the heat around the system. Ideally I'd like...
    • gcleve
    • Thread
    • boiler circulation combi combi boiler heat recirculation pump without worcester
    • Replies: 1
    • Forum: DIY Plumbing Forum
  19. Neville Hillyer

    How can I cure my gravity circulation problem?

    I am a retired Chartered Electrical Engineer and am looking for information about the necessary conditions for gravity primary circulation in a 28mm domestic indirect vented hot water circuit. Until recently I have fitted Hercal cylinders in my house and they always worked without any...
    • Neville Hillyer
    • Thread
    • circulation gravity problem
    • Replies: 99
    • Forum: Central Heating Forum
  20. J

    What is circulation pump time programme?

    Hi All, On my Vaillant thermostat, I have set a timer for my heating to come on daily between 06:30-08:30. I was skipping through the options and noticed timings have been set in the circulation pump time programme by the previous owner (see pic). They have set this for Wed-Fri between...
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