Refilling central heating with heat only boiler problem

Hi All,
I recently got fitted a heat only Worcester Bosch boiler with a separate expansion vessel and Ideal unvented cylinder. At the end the installers spent hours getting the air out by disconnecting and reconnecting the power plug to the Grundfos Alpha2 pump and bleeding the filter under the boiler. They said that it would be better when I have a radiator in the loft.
This was done during an extension and loft conversion so I wasn't ready to have all the radiators fitted so I'm having to drain the system to add radiators. I did it for the first time and added a towel radiator in the loft hoping it would help with refilling the system.
I turned off the boiler, turned the water stopcock off, and drained a ground floor radiator. I installed the loft towel radiator, turned the boiler and water back on, bled all the radiators in the house then started disconnecting and reconnecting the pump while bleeding the filter, as shown by the installers. I was told the pump needs to reach 45w for the system to work. It started at 15w and after 3 hours of trying it only went to 16w. I asked the installers and they said I just need to keep going until it reaches 45w.
I'm struggling to accept that after paying a lot of money for a top boiler and cylinder, I have to go through this archaic process to get rid of the air to have heating and hot water.
Is there a better way to do this? I am planning to incrementally fit another 10 radiators or so and I would like to avoid weeks worth of plugging and unplugging a pump.
Thanks.

I’m not a plumber but I’ve never heard of any thing like that. I've only ever had three heating systems - combi, conventional vented and a sealed heat only system. I just keep topping up and bleeding the rads. Then put the heating on. After a while you can bleed any further air out of individual radiators.

Have they shown you how to add water to your system? What's the current system pressure? Sounds like an airlock in the system, possibly due to poor system design... also sounds like your installers don't know what they're talking about. It's very unusual for a pump to need to run at maximum in order to have a properly working system.

They showed me how to increase the pressure and said to increase it to 2 bar, which is where it is currently. I found them on checkatrade, they had many positive reviews and were fully qualified. They said that it was normal for a house of this size and amount of pipework to need bleeding for this long. It's a three storey property, the first fix (pipe runs) are done for 19 radiators with speedfit stop ends and 6 radiators are currently being used (2 on the ground floor, 3 on the 1st floor and 1 in the loft). I forgot to mention that the boiler and cylinder are in the loft. I turned on all the radiators and turned the heating on as I was told that this would help.

It'll help kill your boiler possibly. They really don't like being run for extended periods with poor circulation or lots of air in the system. Is there any kind of deaeration device fitted up there?

I've just turned it off because it sounds like a vacuum with croaking sounds in the bedroom below. I was told to bleed the filter just below the boiler but there's no air in there, water comes out instantly. The manual for the pump says it automatically vents when you leave it on the maximum setting but it's been on there all day and no progress.

This is what it looks like

muggles said:

Have they shown you how to add water to your system? What's the current system pressure? Sounds like an airlock in the system, possibly due to poor system design... also sounds like your installers don't know what they're talking about. It's very unusual for a pump to need to run at maximum in order to have a properly working system.

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Carcassed with 6 out of 19 rads fitted.....sounds like poor design to me....expecting that to work.

The other radiators couldn't be fitted because the rooms aren't ready yet. I didn't see any other way to do it.

Try opening the zone valves to help clear the air.

Looks like the boiler is at the highest point in the system so there should be a way of releasing the air in the boiler - It should have an automatic air vent in there somewhere. But that would be quite slow, so you may consider a manual air vent T'ed somewhere near the pump because you can't take the casing off the boiler to vent the air.

Tarik said:

The other radiators couldn't be fitted because the rooms aren't ready yet. I didn't see any other way to do it.

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You're not expected, as a customer to know. But a heating engineer should have an idea. As a plumber I would have suggested some temporary connections where your rads are going between the flow+ returns .And what dal5band says in previous post.

The installers came this morning and fitted an automatic air vent at the top of the boiler and it vented all the air instantly. They said that the problem shouldn't happen anymore. Thanks to everyone for their input.