Too Many Radiators

[Weekenders]

We've got some rads in our heating system that are not working correctly.

The property has 4 levels including the cellar.

There are 15 rads in total. Over the years I've upgraded 11 of them, bigger in size or single to double.

Two rads don't heat up fully, one is large @ 40cm x 300cm, the other is average size and in the cellar.

The pump is a Grundfos Selectric 15/60 we run it at 2 and all but 2 rads are working fine. Setting it to 3 does not heat up the two rads mentioned above.

Boiler is a small, old Potterton suprima which needs replacing when it dies. 

The system has been cleaned and drained, no air in the system.                            

Do you think I need a bigger pump? Any suggestions?

Thanks

Sent from my iPad

 

[MickyP10]

Balancing? If you shut others off do the cold pair warm up?

* Not a plumber just thinking out loud.

 

[Phill Peck]

No you probably need a higher output boiler

You can work out the output of each radiator and then find out the output of your boiler

 

[kevindgas]

15 rads, 3 floors on a 15/60 pump there is your problem upgrade the pump to a 25/55 should sort it

basic pump will struggle above 12 rads or 2 floors

 

[DP]

Why have you changed single panels to doubles? Did you calculate the heat loss for the room to fit a matching radiator or just bunged in a double panel hoping to get better heat. Did you alter the plumbing to suit larger output radiators?

 

[Weekenders]

Thanks for the responses,

I did not formally calculate the output required for each room. I wouldn't know how to.

The rooms are large doubles and get cold in winter even though the rads were working and turned up full. I've insulated where possible and changed from single to doubles. I did not change the pipe work for the larger rads. It's running 15mm in most places, nothing smaller. All but 2 of the rads don't work. All the other new doubles are doing great.

Regarding replacing the boiler, when the dial/thermostat is set at half on the boiler the rads that do work get nice and hot so it's not having trouble generating heat at volume it's just getting the hot water to the rads is the problem.

I will try and balancing the system again. Any top tips for doing this correctly?

A new pump will be on the cards if the balancing does not work.

What do the 25/55 and 15/60 pump numbers mean? Would it be a straight swap out in your opinion?

Grundfos UPS25-55 Light Commercial Circulator = £211 inc Vat is that a good price?

Thanks for your help

 

[doitall]

Turn all the rads off except the two problem ones.

If they get hot then it's just a case of adjusting all the others.

have you checked the TRV isn't stuck.

 

[Weekenders]

Thanks, that’s actually great common sense, slightly embarrassed to say I’ve not tried that...

and I'm guessing a TRV = a Thermostatic ???? Valve ???

Thanks

 

[doitall]

Yes, very common for thermostatic valves (Trv's) to get stuck during the summer.

 

[JohnD]

in cold weather, with all your rads fully hot, does the boiler run continuously at full power?

If so, that is a rough indication that the boiler has insufficient power.

When balancing rads, the Flow (input) pipe, and the top of the rad, should be "too hot to hold" and the Return pipe should be "too hot to hold for long." This might be hotter than you were expecting, but it will give the best output from the rads.

There is as far as I can see (an informed householder, not a pro) no problem in having rads which are oversized for the room, as it means you can heat the house faster from cold, e.g. when you have been away, and it will also be able to cope with exceptionally cold weather. However this only applies if the boiler has enough power to heat all of those rads (for example, my house calculates at about 12kW requirement at 0 C outside, but the rads total about 20kW output, and the boiler has max of 24kW output. I chose to do that because my previous 15kW boiler was incapable of keeping the house warm in exceptional winters, even when running continuously, and if you ran a bath, you could feel the house cooling down while the cylinder reheated. My new boiler very rarely runs flat out, only when it is heating the rads and house from cold)

It will be useful if you tell us what insulation you have in the loft and walls (if they are cavity); and do you keep the internal doors closed when the heating is on? There may be some other ideas on saving heat. If you have a conservatory, for example, it will have a huge heat loss.

BTW when I changed from my old Potterton Flamingo to a Viessmann Vitodens, the gas usage dropped from typically 1600 cu metres per year to 1060 cu metres per year, even though last winter was exceptionally cold. This was a much better saving than I had anticipated. Last time we had an exceptional winter, in 2005/6, the old boiler used 1800 cu m..

 

[Weekenders]

Thanks

The boiler does turn off when on full, from what I can remember.

The house is 1890, end of terrace, so no cavity

This year ,

Ripped out the loft room ceiling and put in 75mm Celotex, pulled up the floorboards and put in 200mm rolls. This room no longer gets crazy hot in summer(judging by the last few days) and is so much quieter, look forward to seeing how it performs in winter as last year we slept with hats on ! previously it was Plaster board, Felt, Tiles and the outside world...no insulation at all.

All outward facing walls (where possible) have had 25mm Celotex, baton and plasterboard, the end of terrace walls got very cold.

We have double glazing in all but two rooms, we don’t have a conservatory

Last night I switched off all but the 2 rads and they worked perfectly suggsting I need to upgrade my pump.

Thanks for your help.

 

[JohnD]

Last night I switched off all but the 2 rads and they worked perfectly suggsting I need to upgrade my pump.

Start by balancing all your rads

 

[doitall]

Last night I switched off all but the 2 rads and they worked perfectly suggsting I need to upgrade my pump.

.

Nothing to do with the pump.

If the index rads work so too will all the others., you need to adjust the lockshield valves until they do.