Well done welcome to the world of gas 👍🏻

Does it need a bypass where the pumps are fitted ? or does the motorised valve open first .

The isolation and non return valve were the wrong way around

@@tomkatgastraining Ahh ok.. thanks!

The bypass is only needed if you have pump over run or the pumps run after the valve shuts so the pump isn’t pumping against a stopped end. Because the low loss header is open all the time they are not need for the boiler pump over run also.

Sounds like a homunculus valve is needed in your situation to aid flow to the loft.

The other pumps

I do it that way so as the valve is opening it doesn’t get the full force of the pump but it makes no odds which way you do it I guess I am still used to commercial work as that’s the way we did it.

It’s not a bad idea but we wire it so the secondary pumps don’t come on until the valve opens and the pump stops before the valve shuts so no need really for auto bypass because no pump overrun .

@@tomkatgastraining thanks Derek, you should be ignoring this and relaxing until tomorrow. Thanks for the reply. Makes sense.

Yes you can and the water in the cylinder will need to be heated over 55 degrees centigrade to kill legionella but why would you use a combi what about heat only or system

You would still draw the cooler water coming back on the return

I would only use a plate if I wanted to keep the primary and secondary system separate say if you wanted the boiler on sealed and the heating open vented

Yeh

As close to the boiler as practical on the return pipe is always best

@@tomkatgastraining Thanks mate

Not for low loss headers

There is a video on magnetic filters and how to use a magnacleanse

kzfaq.info/get/bejne/arihhJhqyaiYmmQ.html Here is the link 👍🏻

@@tomkatgastraining Thanks!

A plate heat exchanger completely separates the two systems you can even have one side vented and one side sealed

I think the system dirt would rule out the plate heat exchanger on larger commercial installations. ?

@@mixer7586 fitted plate heat exchanger in commercial jobs and had no problems

@@tomkatgastraining then why the need for low loss headers if total hydraulic separation can be achieved by plate heat exchangers? Cost?

Flow rates not good enough through plate heat exchangers??

Yes they do

@@tomkatgastraining ok thank you. If you were replacing a system boiler for a heating only boiler with separate pump and expansion, would you put the pump on the return or the flow? Thanks

@@jonnyf9088 pumps go on the flow on heat only boilers

@@tomkatgastraining thanks - how come they are different?

@@jonnyf9088on combi boilers the pump has to go on the return because of the diverter valves and a system boiler is just a combi. On the heat only it goes on the flow because of the controls.

I think I explained why and why not so if you skipped through the video you probably missed it

Why split your home into 8 zones unless you have a mansion. The less zones the more efficiency you get on a low temp system. If you're having multiple external pumps you will need seperation with close coupled tee's or LLH

@@Anthony-dh3ty Thanks Anthony. I have a 4700sf house with lots of high ceilings and rooms that are open to each other. Plus 2000 sf of windows. I bought the house in 2016 and it came a cast iron boiler with 8 zones. But Anthony, you are absolutely right, the zones reduce the heat dissipation and therefore it was a stupid design. Lots of energy was lost up the flue. Therefore, I opened all of them up, and added Power Off Delay relays to the circulation pumps (one for the underfloor heating, and one for the baseboards), thereby pulling as much heat as possible from the cast iron heat exchanger and sending it to the living areas. Since heat los is proportional to Delta T, I think Ohms Law (Current = Voltage/Resistance). is applicable to heat transfer as well as electricity. I would say (Heat Transfer = Delta T/ Heat Resistance). In other other words, heat goes up the chimney AND it goes into the baseboards. How fast it is transfered is inversely proportional to on the heat resistance. The faster it goes into the baseboards (by opening all of them up), the less goes up the chimney. Ever since I made this changes, my heat bill dropped by 30% year to year (326Terms to 212 Therms in February). My house is much more comfortable at lower temps - my body is not radiating heat to cold objects in adjacent rooms. There is another advantage. In December, I lowered my temperatures so much that one of the pipes froze. Even though the basement was 46F, the non moving water temp was lower. I was lucky it was not a hard freeze, so it did not burst. Now that I have my pumps running nearly constantly, the pipes will not never freeze, since the water temperature never drops below my basement set temperature of 46F. By the way, I have a TACO 007 which pulls ½ amp (60watts), so my electric cost is $0.15 /day. By the way, I still don't understand why a person with a single boiler needs a LLH, instead of just leaving the pumps running. As long as the pump are running, there is no thermal shock to the heat exchanger. Besides, an efficient system exists when the return water temperature is low. A LLH increase return water temp, reducing efficiency. Whereas a constantly running pump guarantees low return temperatures.

We all make mistakes 😁

@@tomkatgastraining sorry Derek I love your videos and direct people to your utube channel. Ypur knowledge is fantastic and you are a great teacher. This subject though is very misunderstood and I get continual questions from confused engineers on this topic.

@@andrewmillwardwatford9410 as I said in my video there are a lot of guys like you on KZfaq who can explain this subject a lot better than I ever could and that’s why I called it an introduction yes I could have gone on about mass flow rates but most guys who watch my videos don’t care about that they just want to know the basics at the beginning and then work their way into it so I just try and keep them interested because as soon as you mention maths they turn off. You could also argue a little knowledge is a dangerous thing but in this situation it’s just an introduction. I appreciate your interest in my video it means a lot and hopefully I haven’t offended you to much with my mistakes. Cheers for watching and your comment 👍🏻

Thanks for your reply.