No faults but little heat

[Jameswren]

I'm having problems getting our rads hot and need some help before I tear the remaining 10% of my hair out. I'll try and keep it brief but there's a lot of details to get across.

Since we moved to this house about a month ago, we have:
*Replaced the tank in the loft (the old one was made from asbestos)
*Had a new bathroom installed (bath, basin, toilet, shower & pump)
*Had to fix a burst pipe (I put a screw in it)
*Had a leaking rad (replaced yesterday along with 5 others)

Today we have very little heat from the radiators although it hasn't been fantastic since we moved in. The hot water to the sink and bath is red hot.

The condensing bolier (Glow Worm 15Hx) has no faults displayed, nor does the Danfoss control point - there is a thermostat in the converted car port which was flashing to alert us the batteries were running low on juice so I replaced them earlier.

The work done on the radiators, yesterday, seemed of good quality although one radiator has a very, minor drip which the plumber is returning to fix tomorrow.

The house is on three storeys, with 8 radiators (two were a lot newer so not touched yesterday plus they were in the converted car port/kitchen and seem seperate from the rest) with a tank on the top floor and a small, red, spherical tank next to it (header tank?).

We are getting some heat to the radiators but not very much - they were heating quite well prior to replacement but never for long which I assumed was to the dropping pressure from the leaking rad.

It may be me not understanding the Danfoss controls - whichever setting I configure it seems to make no difference. I get the feeling it's me/the controls rather than any actual plumbing but can't seem to get it going whatever I try.

 

[jackthom]

Most obvious question is has the heating temperature control been turned down on the boiler ?

Are some radiators getting very hot while others are luke warm? It may just be that the system hasn't been balanced well.

Also check the setting of the room thermostat and see if the room it's in ever actually gets to the set temperature.

 

[scatmanjohn]

Today we have very little heat from the radiators although it hasn't been fantastic since we moved in. The hot water to the sink and bath is red hot

When a customer says that to me i would be checking the zone valves/ mid position valve (dependent on what system you have).

What type of system do you have?

 

[Jameswren]

Hi Jackthom

Is the heating temperature control you refer to on the boiler? That hasn't been changed and is set at a "high temperature" - it's showing 80 on the Glow Worm's display.

One rad on the top floor was getting pretty hot but not too hot to touch for long - the rest were all luke warm across the whole rad (not cold tops or bottoms).

The room thermostat was set to 27+ to try and rule that out - the actual reading was at 18 when I left this afternoon.

 

[Jameswren]

Hi scatmanjohn

Sorry to be completely lay but I'm not sure what sort of answer I should give! The only info I can give is in the original post - condensing boiler with hot water tank in a cupboard on the second floor. What else do you mean?

 

[jackthom]

Hi Jackthom

Is the heating temperature control you refer to on the boiler? That hasn't been changed and is set at a "high temperature" - it's showing 80 on the Glow Worm's display.

One rad on the top floor was getting pretty hot but not too hot to touch for long - the rest were all luke warm across the whole rad (not cold tops or bottoms).

The room thermostat was set to 27+ to try and rule that out - the actual reading was at 18 when I left this afternoon.

When the heating has been on a while, pick a radiator and have a feel of the pipe where the heated water enters it, just to check that the boiler is definitely providing very hot water.

If that's stonking hot but the actual radiator isn't, then there isn't enough flow through the radiator. First thing to check is that both valves on the radiator are sufficiently open. Turn the thermostatic valve on fully and try opening up the lockshield valve half a turn.

If the boiler isn't running at full power even when the radiators aren't very hot, the overall flow of water through the radiators may be too restricted.

 

[Jameswren]

Hi Jackthom

Is the heating temperature control you refer to on the boiler? That hasn't been changed and is set at a "high temperature" - it's showing 80 on the Glow Worm's display.

One rad on the top floor was getting pretty hot but not too hot to touch for long - the rest were all luke warm across the whole rad (not cold tops or bottoms).

The room thermostat was set to 27+ to try and rule that out - the actual reading was at 18 when I left this afternoon.

When the heating has been on a while, pick a radiator and have a feel of the pipe where the heated water enters it, just to check that the boiler is definitely providing very hot water.

If that's stonking hot but the actual radiator isn't, then there isn't enough flow through the radiator. First thing to check is that both valves on the radiator are sufficiently open. Turn the thermostatic valve on fully and try opening up the lockshield valve half a turn.

If the boiler isn't running at full power even when the radiators aren't very hot, the overall flow of water through the radiators may be too restricted.

Would that explain why the rad on the very top floor was the hottest by far?

Is your response suggesting the system needs balancing?

 

[scatmanjohn]

What else is in the cupboard with the "hot water tank" (Real Name=Cylinder)

Owt like this

If they are not in the cupboard with the cylinder they will be somewhere else, maybe near the boiler.

 

[jackthom]

Hi Jackthom

Is the heating temperature control you refer to on the boiler? That hasn't been changed and is set at a "high temperature" - it's showing 80 on the Glow Worm's display.

One rad on the top floor was getting pretty hot but not too hot to touch for long - the rest were all luke warm across the whole rad (not cold tops or bottoms).

The room thermostat was set to 27+ to try and rule that out - the actual reading was at 18 when I left this afternoon.

When the heating has been on a while, pick a radiator and have a feel of the pipe where the heated water enters it, just to check that the boiler is definitely providing very hot water.

If that's stonking hot but the actual radiator isn't, then there isn't enough flow through the radiator. First thing to check is that both valves on the radiator are sufficiently open. Turn the thermostatic valve on fully and try opening up the lockshield valve half a turn.

If the boiler isn't running at full power even when the radiators aren't very hot, the overall flow of water through the radiators may be too restricted.

Would that explain why the rad on the very top floor was the hottest by far?

Is your response suggesting the system needs balancing?

Basically yes.

There has to be sufficient flow through the system as a whole so the boiler can be kept busy running at full power until everything has heated up.

In addition to that there is a balancing act required if, because of the layout of the plumbing, some radiators don't get as much flow as others.

There's a bit of info about balancing in the FAQs.

 

[Jameswren]

What else is in the cupboard with the "hot water tank" (Real Name=Cylinder)

Owt like this....,

Yes - top one is exactly what we have, second one looks very similar to another item but not the bottom picture.

 

[Jameswren]

Jackthom - I know a little about balancing but will read again, thanks.

There's so many components to the system here it's difficult to track! My other house has a combi boiler and that seems very simple.

We've been out a while and come back to a much warmer house but some rads are still cool/cold.

I've had the Danfoss controls set to "all day" but the heating definitely hasn't been on all day - maybe it's me being rubbish or a fault there(?).

 

[cantaloup63]

Out if interest, what does your plumber have to say about it? If he isn't up to diagnosing the problem, maybe he could at least bring himself to explaining what sort of system you have so that you can seek further advice on here

 

[jackthom]

If you have model numbers for the Danfoss controller / room thermostat it might shed some light on the problem. Is the room thermostat programmable or just a simple one?

 

[scatmanjohn]

Ok ..the second picture is a mid position valve,

Turn on the heating . (hot water off)

Feel the pipes on either side of the mid position valve.

Only the pipe that goes to the radiators should get hot.

 

[Jameswren]

The Danfoss controller simply says "Danfoss" on the front. Under the flap it has three different numbers in separate places so I'm unsure which is relevant to a model number:

FP715-Si
P.N. 38072
087N7898..

The thermostat has no brand name or numbers - it has a symbol looking a bit like infiniti. There's an up arrow, down arrow and a button with a light bulb and frost symbol.

Thanks for everyone's help so far - kids have been freezing!