Heating System - Your Thoughts/General Advice

[LeeBuckman]

I live in a fairly large house that is over 3 stories and has 22 radiators. The house is approx 8 years old and has a condensing boiler (Potterton) and a Grundfos 15/60 pump with a microbore sealed CH system operating at 1.5 bar.

Last year i put in some bigger radiators as the original house builder had undersized them(fairly normal of them apparently) Whilst the house is a lot warmer, it still does not heat up as quickly as i would like. Does anybody have any advice on the following :

1. The central heating pump speed. This is currently set to 2.

2. Getting bigger radiators - Should i just get some larger radiators with the view that the place will heat up quicker as by definition the rads are bigger.

3. TRV valves. I have noticed a couple of the rads in the house have the TRV valve and lockshield valve on the wrong ends. I have read somewhere on the internet that the TRV valve on the wrong end can cause problems in that the water pressure is not enough to lift the ball in the valve. The rad in question is the 'slowest' to heat up ?

4. A lot of rads seem to be a lot cooler at the bottom than the top. I know there is no sludge in the system as i have checked. Could this be because i have shut the lockshield valves down on some to almost closed (not even open 1/4 of a turn !) ?

Thanks In advance for your valued views/opinions

Lee

 

[dcawkwell]

Hi

I have a similar house with similar radiator number.

With high ceilings my house is also harder to heat.

You can calculate correct radiator size for each room.

I think Wickes do one a handy little table. Use only double radiators with double convectors.
Place radiators under windows to block any cold.
Thick curtains and plenty of insulation.

Your heating pump definitely needs to be 3 for 22 radiators don't know
what plumber thought only 2 would be ok for a house that size.

I suggest switching the hot water off at the controller assume you are not using a combi boiler. If some of the flow is going to the tank it is not getting to the radiators. Set it so the hot water gets heated up before the
central heating is needed.

With 22 radiators I would think this is two many for just one pump.
I had problems balancing my system to get good flow to all and I would say about 15 or 16 is about the limit for one pump. But this should sort itself as rooms warm up with the TRVs shutting certain rooms off.

Balance the system up. Open all the lockshield a turn and a half then run the system any ones that are cold open up more and ones that are very hot turn down a quarter.

You haven't said the kW of the boiler but on 22 radiators allowing 1.5 kw per radiator you'l be needing a boiler of around 33kW.
You might want to do a whole house boiler calculator

 

[D_Hailsham]

Last year i put in some bigger radiators as the original house builder had undersized them(fairly normal of them apparently) Whilst the house is a lot warmer, it still does not heat up as quickly as i would like.

Did you check that the boiler output was sufficient to supply the additional rad requirement?

Use Whole House Boiler Size Calculator to find your total heating requirement. Deduct 2kW from the answer which is the DHW allowance.

Use Stelrad Elite Catalogue to determine your rad outputs.

The central heating pump speed. This is currently set to 2.

That is the normal setting. If hot water is reaching all your rads, there is no need to increase the speed.

Getting bigger radiators - Should i just get some larger radiators with the view that the place will heat up quicker as by definition the rads are bigger.

See above.

TRV valves. I have noticed a couple of the rads in the house have the TRV valve and lockshield valve on the wrong ends. I have read somewhere on the internet that the TRV valve on the wrong end can cause problems in that the water pressure is not enough to lift the ball in the valve. The rad in question is the 'slowest' to heat up.

It does not matter which end a TRV goes, provided the flow goes in the direction of the arrow on the body. Modern TRVs are bi-directional (two arrows at right angles), so it does not matter which end they go and the control can be horizontal or vertical. The ball of the valve is not lifted by the water pressure. See TRV operation.

A lot of rads seem to be a lot cooler at the bottom than the top. I know there is no sludge in the system as i have checked.

How did you check?

Could this be because i have shut the lockshield valves down on some to almost closed (not even open 1/4 of a turn !)?

Presumably you were trying to balance the system. The typical LS valve's operating range is from closed to 1½ turns open, after that it is fully open. The LS valve controls the maximum flow rate through the rad, which is directly proportional to the rad output. If the rad is low output it wouldn't be unusual to have the LS valve open less that a ¼ turn.

See How to balance a CH system.