Yes dear.
Stick to your manifolds.
Stick to your manifolds.
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A
AlexCarp
You are up at 2 a.m. when you should be in bed for work. Nah. Few want you.
A
AlexCarp
What do you think they should be?
As has been proven.
You assume much, and know little.
If you were in the CC, you would take a very slightly different tack.....so that demonstrates nicely what you are. Which is a pathetic waste of space.
I on the other hand am fully traceable and therefore hide nothing. Those who I respect know who I am and my limitations, abilities and foremost intentions.
It is a comforting place to be and has seen off more convincing challengers than your insipid self.
You assume much, and know little.
If you were in the CC, you would take a very slightly different tack.....so that demonstrates nicely what you are. Which is a pathetic waste of space.
I on the other hand am fully traceable and therefore hide nothing. Those who I respect know who I am and my limitations, abilities and foremost intentions.
It is a comforting place to be and has seen off more convincing challengers than your insipid self.
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Not how it works me ol' mucker
Although to be fair I would need to know the settings of a few parameters too, but I doubt you know what they are, nor how to get the readings in the first place.
A
AlexCarp
What do you think they should be?
A clear fantasist.If you knew me, then you might know how many and what time zones I live in?
So you have no idea
There's surprise.
There's surprise.
A
AlexCarp
You said you were working today. If were as good as you say you are you would be in demand.
I am working thanks.
It's called multi tasking. Facilitated by having a smartphone (hence the signature) and a queue of traffic.
Now. How about answering those questions?
Oh, sorry
You can't
It's called multi tasking. Facilitated by having a smartphone (hence the signature) and a queue of traffic.
Now. How about answering those questions?
Oh, sorry
You can't
A
AlexCarp
Now repeat with more sensible values. As usual, 40kW is the high power needed to make a combi vaguely usable and it pretty irrelevant to heating requirements - the heating load for most properties is much much less than that, if it isn't then it's unlikely to be a property where a combi is sensible ! So say 10kW tops (note he said he has the primary pump on it's lowest setting), and probably much less than that most of the time.Shall I work it out for him?
Flow rate for a 40 kW boiler with a 20C differential is 40/(4.18x20) = 0.478 litre/sec or 478 cc/sec.
Inside diameter of 28 mm pipe = 26 mm or 2.6 cm. So area of pipe = (2.6/2)² x π =5.31 cm².
Velocity = 478/5.31 = 90cm/sec = 0.9 m/s.
Whatever you may say about terminology and whether this is a "low loss header" or not - it's a system that works and it's a system I'd consider (where I couldn't fit in a thermal store, or at least a buffer tank).
The heat carrying capacity of a pipe is limited by the maximum acceptable velocity for noise reasons. This is generally taken as 1.5 m/s. With a temperature drop across the system taken as 20C for a condensing boiler, the carrying capacity of:
15mm = 18.1kW;
22mm = 40.2kW;
28mm = 67.5 kW.
These figures are maximum and may need reducing to account frictional resistance and pump head.
This house has a maximum heating load of about 13kW. 15mm pipe will do the whole heating system for sure. There are two heating zones. 15mm pipe can do each heating zone for sure. But 22mm was installed to the first radiators on each zone to ensure no noise and taking into account frictional losses. A belt and braces approach.
The Intergas combi can deliver 7.8kW to 40.5kW using gas burner modulation. It comes with 22mm connections, not 28mm.
The integral Intergas pump on setting 1 is more than enough to give a minimum flow through the heat exchanger via low-loss header when delivering 40kW.
In theory only 15mm pipe from the boiler's flow and return could be used as 15mm delivers 18kW. Say if 15mm was fitted the boiler would start at 40kW gas rate and very quickly get up to temperature and the controls would modulate it down to its requirements and right down to minimum at 7.8kW eventually. But I believe the Intergas starts up from low and modulates UP. The min flow is still running through the boiler so it is safe. All fine at 40kW.
Now for the low-loss header. The ballpark to size the header is 3 times the area of the boiler's primaries pipe size into the header. This is for fixed rate boilers running at maximum Many fitters use this figure to make their own low-loss headers, so this way will be used. Note that 15mm is more than adequate to supply the full heating load of this house. The area of the 15mm pipe is approx 133mm. multiply this by three and we get approx 400mm in area which is nearest equiv is to 22mm pipe which is approx. 380mm in area. Going over to 28mm would clearly do it of course.
But this system has been fitted with 22mm pipe for the flow and return primaries to the header which is overkill for this system, but does ensure low noise and full flow through the boiler - a Sentinel filter is fitted which may add some small fictional losses, so all is fine. The towel rail across the primaries will add none. The header is 28mm. This acts as a low-loss header for sure. My tests proved it.
So you have 3 pumps circulating water from 2, 22mm heating circuits and you get little or no circulation through the header
I suggest the reason the header is cold is because the 2 heating pumps are just circulating the water around the heating circuits and by-passing the boiler.
I suggest the reason the header is cold is because the 2 heating pumps are just circulating the water around the heating circuits and by-passing the boiler.
A
AlexCarp
I was thinking about packaging this setup for domestic use. A maker could put into smart white casing two smart pumps with check valves and maybe flow switches and an insulated low-loss header, maybe sized at around 80mm diameter (a width less than the protrusion of the pumps). Two sets of heating flows and returns of 22mm can be in the header and connected outside of the casing at the bottom for the return (to avoid gravity circulation into the heating circuits) and top for the flows. A Sentinel filter can be inside the casing with a drain point under. A thermostat can be on the header to prevent boiler cycling as an extra as the stat may be a problem using weather compensation and gas rate modulation.
Different sizes can be made with one having a fixed rate pump for a cylinder.
Then a nice smart box either under the boiler or elsewhere in the house. I am sure many installer would buy such a package. It would be very quick to fit and provide an instant solution to TRVs on all rads and two heating zone.
Different sizes can be made with one having a fixed rate pump for a cylinder.
Then a nice smart box either under the boiler or elsewhere in the house. I am sure many installer would buy such a package. It would be very quick to fit and provide an instant solution to TRVs on all rads and two heating zone.
A
AlexCarp
There are two auto modulating smart pumps on two heating zones, both are off the header. One integral boiler pump circulates water through the header. Three pumps are not circulating around heating circuits at all.
-On startup the boiler pump setting is at 1 and pumps into then header.
-The two smart pumps are on full speed and flow as all TRVs are fully open, together they have more pull that the one boiler pump.
-All of the heat from the boiler is sucked into the two heating circuits. It has to, physics says so.
-As the system warms up the two heating returns get hotter and the boiler gradually modulates down.
-The TRVs close up gradually as the room warms up.
-The smart pumps wind down their speeds and then a point is reached where the boiler pump pumps more than the two combined smart pumps.
-The situation is then reversed. The boiler pump then pumps most of its flow right through the header and directly back to the return to the boiler.
-By this time the system is nearly up to temperature.
-Another point is reached when all TRVs are closed and the electrical flow switches in each heating circuit switch out the boiler.
-All off.
That is how it works. I spent a considerable time testing it.
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