CH Question - downstairs rads..

[Gragson]

Downstairs rads have been taking ages to heat up and have gotten to the point that unless I turn the hot water off they don't heat up at all, seems to have gradually got worse but turning HW off seems to kick it in. Upstairs all hot either way.

The 3 way valve I replaced about 8 years ago and the programmer at least once, maybe twice, the Grunfos pump was replaced about ten years ago.
A mate "who does a bit of plumbing" reckons that the rads/pipes need a flush - he is not a heating engineer by any stretch! Half the rads are newish, 7 upstairs 7 downstairs.

The house was extended about the same time the new pump went in, but not sure if it was matched for extra rads.

I'm thinking an additive and drain down won't hurt, unless it makes things worse! But also suspecting the pump might not be up to it?
Is there a an online tool where you can put the data into and it spits out what your pump should be?

 

[Kayos]

You need a 15/50 or a 15/60. Just a standard pump

Does sound like it's struggling

 

[the snooper]

If it improves when you turn off the hot water have you checked if the pipes into the water cylinder are heating up when they shouldn't be, maybe a diverter valve problem adding to a partially blocked system

 

[S-Rail]

Try going around the upstairs rads and turning the lockshields down by half a turn each , give that day or so and then repeat again if needed .

That would be my first point of call . It’s called balancing . Basically the water is taking the easiest route around the pipe work , upstairs heating and hot water cylinder

 

[Gragson]

You need a 15/50 or a 15/60. Just a standard pump

Does sound like it's struggling

It's a 15/60 fitted, do you reckon it needs swapping out for the same?

 

[Gragson]

If it improves when you turn off the hot water have you checked if the pipes into the water cylinder are heating up when they shouldn't be, maybe a diverter valve problem adding to a partially blocked system

I will check this - thank you

Try going around the upstairs rads and turning the lockshields down by half a turn each , give that day or so and then repeat again if needed .

That would be my first point of call . It’s called balancing . Basically the water is taking the easiest route around the pipe work , upstairs heating and hot water cylinder

I will read up on that and give that a go, never knew that, cheers for the tip

 

[gaz1]

The 3 way valve I replaced about 8 years ago and the programmer at least once, maybe twice, the Grunfos pump was replaced about ten years ago.

thats too old try a play around and see what you get

valve is only guaranteed to work for a few years after that in can fail and depending on your circuit may aim towards your water instead of rads when fails

make sure your rads are equaled as well

 

[voipio]

The water cylinder heating loop provides the least resistance to flow, effectively giving priority to the hot water coming from the boiler, and starving the radiators. Setting the radiators to come on before the water heating, and having the water heating on say two or three times a day for half an hour, or so, should give plenty of hot water in a typical domestic hot water system, and nice warm rads. Set the rads to come on first, for say half or one hour, to give the house a chance to heat up, followed by the water heating. Alternatively, set the water heating to come on for half an hour and then turn off before the radiators, to get the tank hot ready for an early bath/shower, and the rads starting to warm up afterwards. Also check that the thermostatic radiator valves are working properly.

 

[hermetic]

If your downstairs rads are not heating,first remove the screw in the end of the pump and check the shaft is spinning, then turn off the heating and when it is cool, turn off the valves at either side of the pump, and remove the four allen bolts and remove the pump head from the body. Check that the rotor spins freely without catching or binding, and check that the rotor slots are clear and clean, as they can block over time, reducing the pump efficiency dramatically, and an inneficient pump will not drive the downstairs radiators at all! If the pump is not running in the heating position, it is a sticky three way valve, or a faulty microswitch in the valve or maybe even a faulty pump. Much easier to replace a valve than replace the pump, and much easier to put a new head on the old pump body, or a new valve motor/switch assembly on the existing valve, provided it is not seized, and provided it fits!! There is usually a lever on the outside of the valve body to manually move the valve through its three positions (heating, dhw and both) and from cold you can see which pipes get hot to see what is working and what isn't. remember that all the magnetite sludge will settle in the lowest part of the system. Power flushing is good IF it is done properly, which it so often isn't! To manually flush, turn off valve and lock shield, drain and remove each radiator, take out the bungs and flush with a garden hose diagonally whilst giving the rad a good bash with a rubber mallet. If it is a gravity system, go to the rad position with a large bucket, and with your thumb over the pipe end turn on the valve and let water run into the bucket whilst alternately removing and replacing your thumb over the end of the pipe, and when the water runs clear turn off and repeat at the locshield end. repeat for each downstairs rad and you should be good to go! It is a summer job! Don't forget to put corrosion inhibitor in when you refill, and check the loft tank washer and the tank for "debris"
Phil

 

[hunter27]

With the heating switched on and the room stat set on high, slide the lever on the 3 port valve across, it should slide easily, fully in both directions with no spring pressure against you. If you are pushing it against a spring, the valve motor isn't working or no signal from room stat or timer. You can normally latch the valve's lever manually to the CH on position and as long as the boiler and pump are running the rads should then work.
Zone valves and 3 port valves are usually the weakest link on a system. Years ago there was a problem with some pumps where the impeller came loose and would free wheel on the spindle but it was quite rare.
I wouldn't mess with rad valves so long as they are not throttled down too much at this stage assuming it worked okay in the past. The pump should be powerful enough to circulate water without a problem but if the circulation is poor / low it will always take the easiest route.

 

[fizzy]

Downstairs rads have been taking ages to heat up and have gotten to the point that unless I turn the hot water off they don't heat up at all, seems to have gradually got worse but turning HW off seems to kick it in. Upstairs all hot either way.

The 3 way valve I replaced about 8 years ago and the programmer at least once, maybe twice, the Grunfos pump was replaced about ten years ago.
A mate "who does a bit of plumbing" reckons that the rads/pipes need a flush - he is not a heating engineer by any stretch! Half the rads are newish, 7 upstairs 7 downstairs.

The house was extended about the same time the new pump went in, but not sure if it was matched for extra rads.

I'm thinking an additive and drain down won't hurt, unless it makes things worse! But also suspecting the pump might not be up to it?
Is there a an online tool where you can put the data into and it spits out what your pump should be?

View attachment 326733View attachment 326734

Gotten?
Yeall from Texas

 

[the snooper]

If your downstairs rads are not heating,first remove the screw in the end of the pump and check the shaft is spinning, then turn off the heating and when it is cool, turn off the valves at either side of the pump, and remove the four allen bolts and remove the pump head from the body. Check that the rotor spins freely without catching or binding, and check that the rotor slots are clear and clean, as they can block over time, reducing the pump efficiency dramatically, and an inneficient pump will not drive the downstairs radiators at all! If the pump is not running in the heating position, it is a sticky three way valve, or a faulty microswitch in the valve or maybe even a faulty pump. Much easier to replace a valve than replace the pump, and much easier to put a new head on the old pump body, or a new valve motor/switch assembly on the existing valve, provided it is not seized, and provided it fits!! There is usually a lever on the outside of the valve body to manually move the valve through its three positions (heating, dhw and both) and from cold you can see which pipes get hot to see what is working and what isn't. remember that all the magnetite sludge will settle in the lowest part of the system. Power flushing is good IF it is done properly, which it so often isn't! To manually flush, turn off valve and lock shield, drain and remove each radiator, take out the bungs and flush with a garden hose diagonally whilst giving the rad a good bash with a rubber mallet. If it is a gravity system, go to the rad position with a large bucket, and with your thumb over the pipe end turn on the valve and let water run into the bucket whilst alternately removing and replacing your thumb over the end of the pipe, and when the water runs clear turn off and repeat at the locshield end. repeat for each downstairs rad and you should be good to go! It is a summer job! Don't forget to put corrosion inhibitor in when you refill, and check the loft tank washer and the tank for "debris"
Phil

A sure sign of pump not pumping would be the sound of water boiling in the heat exchanger