Radiators not heating house adequately

If you have not already check the balancing valve at the coil on the hot water cylinder. It's usually a gate valve installed at the lower of the two coil connections. If this valve is open too much most of the circulation will be through the coil (giving you plenty of hot water) but the radiators will be effectively bypassed and will get very poor circulation, which will result in lukewarm or even cold rads. The bypass valve should be closed fully, and then opened 1/2 to 1 turn only.

You have to time the burner ON/OFF times with the heating on so not sure what you mean.
Your boiler is factory set at 23kw so those times above will be very informative, ie taken with all rads I/s and with boiler on for at least 2 hrs.

The pump details would also be very informative.

The E.vessel capacity in litres ditto, Is this Citral unit externally fitted because I think that boiler comes with its own 10 litre internal one but your installer may have decided your system required that external one, if fitted.

Edit: my latest info is that your boiler ( if a boiler house model) should/is set to 21 kw output and doesn't have a internal E.vessel

adocholiday wrote: »

Ok I'll take a look when I get home. Just for reference I looked at the manual for the boiler last night and this is the info I got:

Burner: Riello RDB1
Heat Output (factory settings): 23kW
Stat range: 65C -75C

If there's any other info about the boiler needed I can find it. Thanks again all.

One other item to check out even though very unlikely to be your problem.
When the burner cuts out make sure that the circ pump is still running (by feeling/listening to it), it should only stop when the boiler is stopped.

Thanks but how long doe the BURNER run for again before cutting out, I presume that the 2 hours refers to the heating actually being switched on?.
I presume you don't mean burner run time of 2 hours then off for 177 secs then burner firing again for 2 hours?

Very good so the burner cycle time is 414 secs (177+237) and the burner run time % is, (237/414)*100, 57.2% which means the boiler output (=rads output) of 23*57.2% = 13kw.
On would think that 13 kw even in a reasonably well insulated house should be adequate, today my 4 bed cavity BLOCK house is being kept at 21/22C with a boiler output of 7 kw.

Your rads should possibly be capable of > 13 kw output but you would have to measure them up or ask installers for the outputs.
In the mean time have a look at the LED (traffic) lights on your pump (see page 10 of the attachment), and see what they are indicating, take your time and write down the colours and sequence.
If I am interpreting the file correctly then one green is constant speed 1 (lowest and pretty useless), one green followed immediately by one orange is constant speed 2 (reasonably OK for most installations) and one gteen followed immediately by two orange is constant speed 3 and the highest pump setting which will give the greatest circulation and highest rad output but may be noisy.
For the moment anyhow, just see if you can what the lights are indicating.

adocholiday wrote: »

Thanks again all, particularly John. I adjusted the balancing valve as suggested and I bumped up the stat a bit on the boiler. Not sure if it's just a placebo effect but the house was certainly a bit warmer yesterday evening for it. Still nowhere near the heat my parents get with more or less the same setup but that could be down to a host of other factors including their boiler being adjusted to a higher setting than factory. It's also possible that my rads are undersized in the larger rooms but that's another issue. For now I'm just glad there doesn't appear to be anything technically wrong with my setup.

Mickdw's point above is interesting, I have my (Firebird) boiler SP at 75C and I can't keep my hand on the top of the rads (can maybe just for 5 secs or so), I certainly know that they are very hot. I would be surprised if your boiler stat SP and actual water temperature are vastly different but I suppose the only way to reasonably remove any doubt is to get hold of a infra red temperature scanner which, while it won't give you a accurate reading, will give some indication of the true temperature. Another probably easier way (since you have no HW cylinder control) is to measure the hot water temperature with a household thermometer after ensuring no one has drawn off any appreciable amounts of hot water and take the reading at the end of your 2 hour heating period.

Now, assuming (for the moment) that the actual temperature is at your selected SP of ~ 75C then you can consider a number of reasons as to why your house is "cold".

One is that you are simply not letting the heating on for long enough bearing in mind that, from cold it takes ~ 25 to 35 minutes to heat up the system water contents so you are only left with a real heating time of ~ 1.5 hrs in a 2 hour heating period, I'd say my house takes at least this or longer to feel any way comfortable, I have a roomstat (controlling 2 rads) on my main living room area (TRV's on the 8 remaining rads) and I leave the heating on for 15 hours/day with a average heating demand of 5 to 7 kwh/hr depending on the ambient temperature and the wind strength since I have suspended floors.
Re your boiler output vs your parents', if the boiler cuts out within say a max of 35/40 minutes after a cold start then its certainly not underpowered IMO, also it is apparently outputting 13kw when up to temperature and cycling so well within its power output range.

Two is that your rads are simply under sized, when you get the time just measure one of your biggest (or coldest) rooms and then measure the width and height of the rad(s) in this room and use the attachment below to give you its rated output (page 9), for example, assuming a double panel rad with twin convectors, type 22, then a 1200X500 rad will give 1729 watts or 1.73kw and so on, then divide the rad output in watts by the room area (M2) and see what number you come up with.

Three is that your circ pump is underpowered (unlikely) if you have another look at the nameplate you should see its head output in meters(x10), you will see something like Grundfos 15 130 60 its the last two digits that are important, ie the 60, if its 40 then you have a 4M head pump which would be a bit on the weak side in spite of running at its highest setting.

Four (and last?) is that your system has a automatic bypass valve fitted(ABV), fitted in the horizontal bit of pipe in the attachment, with black adjustment knob.
this is rarely but sometimes is recommended/installed with oil fired boilers, its fitted between the flow and return and it may be fitted anywhere but is sometimes installed in the boiler house, fairly close to the boiler, its purpose is to maintain a minimum flow through the boiler and also to prevent boiler overheat at shutdown, if you see one of these anywhere check the setting, it is indexed something like 0 to 0.6 or maybe 0 to 6 (or something like that) and see what its present setting is.

The above will keep you going for the afternoon.