Central heating issues

[Al@n]

Moved into a new property

2 bedrooms which have microbore pipework single radiators

Downstairs 1 single, 1 double and a towel radiator, 15mm pipework

In our previous (larger property) when putting on the central heating the boiler would run at full pelt (I think the term is full rate) where you could hear the fan running etc within a short time frame the house was nice and cosy, albeit it was an ideal vogue combi boiler

In this property we have a Vaillant ecotec pro 28 boiler, I can't hear the fan running when the central heating is switched on and it doesn't appear that the boiler is running at full rate, it takes at least an hour plus for the radiators to get really hot.

When I open the taps I can then hear the fan run and the boiler run at full rate!

Is this normal behaviour for the vaillant boilers when running central heating?

I also found this part underneath the floorboards any ideas what this is? Has it been set correctly, could this be causing the above mentioned issues with the central heating?

 

[Jurassicspark]

My Valliant Ecotec sustain is merely quiet on heating but sounds like a jet engine when first starting for HW.

First of all, you need to check if your system is balanced correctly.

Is there enough pressure in the boiler? 1.5 bar approx.

 

[Al@n]

My Valliant Ecotec sustain is merely quiet on heating but sounds like a jet engine when first starting for HW.

First of all, you need to check if your system is balanced correctly.

Is there enough pressure in the boiler? 1.5 bar approx.

Pressure is fine, appear to be balanced ok but I do not think that would affect the behaviour of the boiler which is the same as yours i.e quiet when running central heating but very loud when running hot water.

 

[Jurassicspark]

What is the flow temperature set to on the boiler?

What controls the boiler?

 

[Al@n]

What is the flow temperature set to on the boiler?

What controls the boiler?

Set to 75 degrees

External control Honeywell cm927

From you descriptions it appears your boiler is operating the same as mine!?

 

[Jurassicspark]

How long does the boiler take to reach set desired temperature?

Does it turn on and off within a short period of time? Do the pipes to the radiators feel hot?

The required boiler output does depend on the total heating capacity of your radiators. There's no point trying to put 20kW from the boiler into 10kW of rads.(example) The rad temperature will rise very quickly, as will the return temp, so the boiler will modulate down. If the boiler can modulate below 10kW that's fine; but if it can only modulate down to 15kW the boiler will go into on/off mode, which could explain why it is taking so long for your house to reach temperature.

70% of the time, an incorrect unbalanced system was the cause of slow heating.

Is the house insulated? Windows, and doors double glazed?