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It’s not quite like that… The boiler theoretically produces .388l water per second at 82 degrees. But because of the flow issues upon which we are still deliberating; the real temperature but the time the water has travelled to most of the rads is somewhere between 70 and 75 degrees. I am not...

I have sent you a private message.

I think I am getting it now - the problem in my thinking was that for some reason I was adding the loss requirement of the emitters in l/s to the flow requirement of the boiler l/s. It was my obsession with the bypass and it's needs and the needs of the boiler confusing me. This was leading me...

Yes that’s what I meant. No Yes I didn't ever attempt any other setting than 3 on the pump. I’ll check 2 But what I am thinking is – would the system ever make the design 9 degree drop with such a huge primary circuit and a largish head? I see your point… I am thinking about...

I have installed the 15-60 and refitted the bypass with a gate valve and removed the ABV. In fact I just re-made the entire bypass loop out of 22mm, coz the old one was a bit of a dog end. Where I am at now is the following. All the rads are set to give a 22 degree drop. The house is...

Thanks heatingman. I drained the system today and re-installed a permanent 15mm bypass loop with a gate valve on it. In fact I just bridged the existing 22mm bypass circuit with the ABV in it. ASCII art coming up... ---- Something like that where the primary flow is not shown to the left of...

It appears I was wrong - this is a familiar feeling now :lol: The actual Head in the index circuit is 4.55m @ 11 degrees drop. The reason why I got it wrong was forgetting that the full section mass flow only travels in the 22mm pipe and not the 15mm spur to each emitter. Now it's...

I really am out of my depth here - but I have a proposal... I could T into the feed and return on the primary circuit in the cellar. With an ABV on a short pipe between the two proposed T's. Where I am thinking of doing that the head would = 2.29m .4l/s inc boiler. So, if I stuck another...

I have completed all the calculations now. Unfortunately the total resistance in the index circuit is 6.28m. This might be a tad over what it really is, but not allot I am afraid. I did notice that in the run right from the pump to the 1st Tee, the heat mass index required was 0.55 which is...

Re checked cacls the actual pipe distance should have been 34.9m - therefore Head is actually 3.153 M.

"It's worse than that Jim" The actual calculated length for the pipes to and from the pump when I worked it all out properly with a tape measure was 19.9m @ 22mm. There are 2 tees right out of the boiler - a short stub ontop for bleeding. The main flow, therefore does a sharp right angle...

Thanks for the reply - I think my calculations were for a 323w rad. But we arrived at almost the same figures... I was in a bit of a hurry - but your example has made it clearer. I closed the LSV's to check the system balance. I could have just closed all the TRV's for what I was aiming to...

The flow and return temperature variation now with the system going full pelt trying to re-heat the house is 30 degrees - return = 44 flow 74 degrees at the boiler. Ovbiously something is very wrong? Maybe the pump is broken - or the Magnaflow I fitted has enormous flow resistance?

The distance between the boiler and the pump is about 7m 22mm there and the same back on the return - in other words it's 7m + 5 right angle 22mm turns each way on the primary circuit. What seems to be happening is that even with all the LSV's in the system now all closed and the ABV valve...

Whatever the units are in the leflet you pointed me at Copper Pipe Sizing. Agreed - I have missed out 2 elbows and 4m of 22mm pipe, between the pump and the t's into the 15mm index branch I spoke of. No The bypass is 22mm I have a PTS own brand bypass. That is exactly what...

Sorry before you say it - there are three other Rads on that index circuit so that figure looks wrong - the required Heat is 0.06 for all the Rads combined - so that will make sense against the .67392 figure now :!:

I had written out my reply but the browser timed out and I lost it. I also don't know who to quote - sorry. My index circuit is 37.44m 15mm. That gives a dynamic resistance of 0.67392 whatevers... The required mass flow index is 0.007022 since it's a 320w towel rad, so no great shakes there...

Think I've sussed it now. Thanks David (assumption on the "D" ) I found the boiler installation manual. It states the correct installation pressure where the boiler is to be installed into a sealed system is 1.5 Bar. This therefore means that the static pressure in the system will be 1.5 bar. I...

So far as I can work out, rad companies output figures are all quoted against a temperature differential of 50 degrees. Meaning, the hot water enters the rad at 82 degrees, but the room is 50 degrees cooler. This means they will provide their rated output up to about 32 degrees room temperature...

Thanks very much - Mr Hailsham for those answers. The Boiler is Myson Fanfare 30/50si unit. Which has been very reliable for at least 15 years now and shows no signs of any problems at the moment. The total wattage of the Radiators is 16.6KW - the total loss of the house is 11.00kw. So the...