Low loss header stall.

[@Sefolli_Klodjan]

Absolutely agree with this theory nicely explained by you

[@HeatGeek]

Excellent video! Not heard of this before! Well done

[@COUPEDUMMY]

Hi just come across your video. Was looking at a commercial system today with three secondary circuits with a vertical LLH configuration the same as pictured. Heating ct , one small ct and small vt circuits. When the two smaller circuits are operational alone, the temperature drop between primary flow and secondary flow is only about 5 degrees. When the much bigger ct pump is switched on, the secondary temp dips hugely with about a 20 degree variance between primary flow and secondary flow on the llh and as you say partial stalling…the concern with this is that the one ct circuit serves calorifiers that need to be stored at 60 degrees. We are getting about 45-50 degree delivery to the calorifiers at this point which is causing legionella concerns. So, ideally we need to be balancing pressures I assume.

[@andrewmillwardwatford9410]

Can you see a high primary return temperature?

[@COUPEDUMMY]

@@andrewmillwardwatford9410 no very low. Pretty much the same as the secondary flow temperature when all circuits are live. I’m suspecting the LLH is too small for the system.

[@pfischer4664]

Hi Andrew, confused by the flows here .... or am I misreading your digram @2:07. 60+40 going in and 55+40 going out ?

[@andrewmillwardwatford9410]

Sorry was poor diagram.

[@cliveramsbotty6077]

Thanks Andrew I really do enjoy these theory videos you put out, very interesting. Do you have any recommended sites or books or papers I can read up on to learn a bit more about how thermal energy moves around in water? cheers

[@BelugaMike]

Hi Clive. You have already found an excellent resource. I am learning this stuff too, here is some what I have found. Caleffi have loads of excellent videos and an online magazine. Dan Holohan books are very interesting, also a little US centric in some of the issues they address. CIBSE Design Guide. Some very useful sections in Heating and Air Conditioning of Buildings by Doug Oughton. I did the Heating Academy Northampton hydronics course. Its meant to be the basics of hydronic design but as a beginner was also exposed to lots of other useful information and was a very enjoyable couple of days. Let me know what you are using.

[@Allegedly2right]

T1 40c T2 42c no external heating, Heat pump has an inbuilt pump and after the low loss header a pump 3 settings on the 2 pumps how do you get them to run in tandem.

[@andrewmillwardwatford9410]

Can you explain your question in more detail please

[@Allegedly2right]

@@andrewmillwardwatford9410 Happy New Year Andrew I will get back to you nice one

[@Allegedly2right]

@@andrewmillwardwatford9410 Andrew thank you for showing a interest I have a Grant Aeroa3 17kW with a low loss header t1 goes in at 40c mixes and doesn’t transfer the 40c to the radiators is seems to go the easiest route our of t2=Flow&Return the pump in Aerona has 3 settings and the ancillary pump has 3 settings also how do I get the 2 pumps on at the same time.Haha I know get a heat pump engineer some guy that did a 2 week course Engineer £100 to £200:call out fee.Cheers Andrew if you have any ideas much appreciated.4 bedroom on 2 floors 10 radiators Bathroom no trv

[@andrewmillwardwatford9410]

@@Allegedly2right google my name and call me

[@asif530]

Yes this would be a problem or more of a problem on the horizontal position if you don't size the pump or pumps correctly on the secondary side. I agree why bother with horizontal LLH . Unless you really have no choice.

[@denispaton6102]

A low loss header to me just seems like an automatic bypass that is more likely to fail if not fitted vertically?

[@andrewmillwardwatford9410]

Not at all like an auto by pass..