Balancing heating system including U/F heating

I've been fiddling with a number of rads in our badly piped-up house over t he last few weeks to encourage some unenthusiastic radiators to start heati ng up. I've not got a thermometer to balance properly, so I'm largely just going through the process of throttling back the locksheild valves on the well behaved radiators until I start to achieve some balance. Largely nil effect so far (though some occasional glimpses of success).

However, it just occurred to me that the largest rad in the house is in fac t the wet UFH in our kitchen, and whilst that is nice and toasty and warm i t may well be the largest single drain on the supply.

The whole system is very imperfect. From a WB combi, we have effectively tw o zones - the UFH zone and the radiators. The hot spewing forth from the b oiler goes to the rads (presuming there is a call for heat from the thermos tat), and if there is also a call for heat from the thermostat for the UFH then that sucks up part of the supply too. When the main thermostat demand s no heat, the UFH thermostat has no live power supply, and therefore the U FH cannot call for heat in its own right - the UFH can only operate when th e main stat calls for it.

I'm sure this is far from ideal, but the consequence is that we have always set the thermostat for the UFH to demand heating whenever the rads are cal ling for it (by setting the UFH thermostat at the lowest level possible). We worked on the presumption that we always wanted some heat in the floor, and didn't consider that there might be some impact on the rest of the syst em.

Is there likely to be an impact? I *think* that the UF zone and the rad zo ne divert from one "T" of 15mm piping. There is a pump on the UFH, so I pr esume there is a maximum flow which it can possibly draw away from the rads - assuming the pump in the UFH is less powerful than the pump in the boile r.

Or am I barking up the wrong tree considering whether the UFH is having any impact at all on the balancing of the rest of the system?

TIA!

Matt

Reply to
larkim
Loading thread data ...

Does the UFH not have a manifold with a mixing valve and a flow throttling valve so that you can reduce its demand ?

AWEM

Reply to
Andrew Mawson

I presume it does, yes, so perhaps that might be an area to fiddle with to get the temps up.

Matt

Reply to
larkim

the last few weeks to encourage some unenthusiastic radiators to start hea ting up.  I've not got a thermometer to balance properly, so I'm largely just going through the process of throttling back the locksheild valves on the well behaved radiators until I start to achieve some balance.  Largel y nil effect so far (though some occasional glimpses of success).

act the wet UFH in our kitchen, and whilst that is nice and toasty and warm it may well be the largest single drain on the supply.

two zones - the UFH zone and the radiators.  The hot spewing forth from t he boiler goes to the rads (presuming there is a call for heat from the the rmostat), and if there is also a call for heat from the thermostat for the UFH then that sucks up part of the supply too.  When the main thermostat demands no heat, the UFH thermostat has no live power supply, and therefore the UFH cannot call for heat in its own right - the UFH can only operate w hen the main stat calls for it.

ys set the thermostat for the UFH to demand heating whenever the rads are c alling for it (by setting the UFH thermostat at the lowest level possible).  We worked on the presumption that we always wanted some heat in the flo or, and didn't consider that there might be some impact on the rest of the system.

d zone divert from one "T" of 15mm piping.  There is a pump on the UFH, s o I presume there is a maximum flow which it can possibly draw away from th e rads - assuming the pump in the UFH is less powerful than the pump in the boiler.

ny impact at all on the balancing of the rest of the system?

The pipework resistance in most UFH systems is much higher than radiators making balancing virtually impossible. This is why the UFH usually has it's own separate pump and manifold and can be considered a separate system. If you haven't got this, this may be your problem

formatting link

Reply to
harry

last few weeks to encourage some unenthusiastic radiators to start heating up. I've not got a thermometer to balance properly, so I'm largely just going through the process of throttling back the locksheild valves on the well behaved radiators until I start to achieve some balance. Largely nil effect so far (though some occasional glimpses of success).

the wet UFH in our kitchen, and whilst that is nice and toasty and warm it may well be the largest single drain on the supply.

zones - the UFH zone and the radiators. The hot spewing forth from the boiler goes to the rads (presuming there is a call for heat from the thermostat), and if there is also a call for heat from the thermostat for the UFH then that sucks up part of the supply too. When the main thermostat demands no heat, the UFH thermostat has no live power supply, and therefore the UFH cannot call for heat in its own right - the UFH can only operate when the main stat calls for it.

set the thermostat for the UFH to demand heating whenever the rads are calling for it (by setting the UFH thermostat at the lowest level possible). We worked on the presumption that we always wanted some heat in the floor, and didn't consider that there might be some impact on the rest of the system.

divert from one "T" of 15mm piping. There is a pump on the UFH, so I presume there is a maximum flow which it can possibly draw away from the rads - assuming the pump in the UFH is less powerful than the pump in the boiler.

impact at all on the balancing of the rest of the system?

It ain't going to work very well if the UFH can't be on without the radiators because the UFH has a lot more thermal inertia and needs to come much earlier in the morning.

It would be usual to have the equivalent of an S-Plan system with the UFH and radiators in separate zones - each with a zone valve controlled by a thermostat, and wired so that the boiler only runs when either one or both zones are calling for heat.

Because the water circulating through the UFH needs to be at a much lower temperature than that going through the rads (typically 40 degrees rather than 70 or 80) there should be a mixing valve which controls the temperature by mixing return water with newly heated water. There should be a dedicated pump which circulates water just round the UFH circuit, whilst the main pump runs the radiators and delivers newly heated water to the UFH circuit (but not round it).

I think that you need to make a close examination of what you've actually got, and then work out what needs to be done to make it work properly. Inserting a couple of zone valves and a bit of wiring shouldn't be too difficult, and might make a dramatic difference.

If there's a lot of contention between zones, you could arrange the timing so that they're not often on at the same time.

Reply to
Roger Mills

er the last few weeks to encourage some unenthusiastic radiators to start h eating up. I've not got a thermometer to balance properly, so I'm largely just going through the process of throttling back the locksheild valves on the well behaved radiators until I start to achieve some balance. Largely nil effect so far (though some occasional glimpses of success).

fact the wet UFH in our kitchen, and whilst that is nice and toasty and wa rm it may well be the largest single drain on the supply.

y two zones - the UFH zone and the radiators. The hot spewing forth from t he boiler goes to the rads (presuming there is a call for heat from the the rmostat), and if there is also a call for heat from the thermostat for the UFH then that sucks up part of the supply too. When the main thermostat de mands no heat, the UFH thermostat has no live power supply, and therefore t he UFH cannot call for heat in its own right - the UFH can only operate whe n the main stat calls for it.

ways set the thermostat for the UFH to demand heating whenever the rads are calling for it (by setting the UFH thermostat at the lowest level possible ). We worked on the presumption that we always wanted some heat in the flo or, and didn't consider that there might be some impact on the rest of the system.

d zone divert from one "T" of 15mm piping. There is a pump on the UFH, so I presume there is a maximum flow which it can possibly draw away from the rads - assuming the pump in the UFH is less powerful than the pump in the b oiler.

any impact at all on the balancing of the rest of the system?

Cheers. Yes, there is a separate manifold and pump for the UFH system. An d for practical purposes, the UFH does in fact work well, even though it ca n't call for heat without the rest of the system demanding heat too, though I agree it is slightly peculiar that it can't operate of its own devices.

I know that it isn't "right", but (as far as the UFH goes) it works. And n ow that others have posted that there is unlikely to be a conflict between the UFH and the radiators in terms of balancing pressures, I think we'll le ave well alone!

Thanks for taking the time to respond!

Matt

Reply to
larkim

HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.