Is my new heating system working suitably?

Det Somerset · 05-02-2014 10:56am #1

I posted a different but closely related query elsewhere on Boards yesterday, but thought this question would be more suited to a new thread in this sub-forum. Apologies if this was the wrong approach to take.

I bought a large 2500 sq ft bungalow last year. It was an old house and had been unoccupied for maybe 3-5 years. I had major renovations done to it, including a new heating system and radiators and as much extra insulation as I could afford. Since we moved in before Xmas, we have been using the heating very sparingly as we couldn't afford to fill the oil tank significantly at the time. Over the last week or so, we have been trying to heat up the house more suitably and have found that the natural 'cold' temperature of the house is around 12 degrees and if we have the heating on for 4 hrs straight the temperature rises to about 17 degrees, so it seems that we get a rise of just over a degree an hour with the heating on. I would have thought this to be slow and possibly insufficient but I'm not an expert so would appreciate some opinions on whether that is normal for a house of this size or poor. There are three possible explanations that I can think of here ...

1. As has been explained to me by both the builders and another helpful poster on Boards, the floor slab and walls of such a property would still be damp and as a result the rooms will be naturally colder and probably slower to heat, which is what I'm experiencing now but this will improve suitably over time.
2. I've gone from a standard 3 bed semi which heated up a lot quicker, to a sprawling large roomed bungalow with a number of high ceilings which just takes a lot longer to heat and I'm foolish to think it will heat any faster.
3. The radiators are not suitable to heat the size of rooms we have and should be replaced.

As additional information, the radiators seem to reach close to full temperature after about 20 mins of turning on, they are then too hot to keep hold of so it's not that they aren't heating sufficiently. Due to the renovation costs rising far above our budget, we can't currently afford to burn oil endlessly to heat the house just for comfort. That said, if we could be certain that doing so for a day or two would dry the house out and then make it easier to heat going forward, we'd do that. Or, if it was felt here that the radiators sound like they are insufficient, now would be the time to talk to the builders about that as they are still finishing off snags. But if we just need to accept that this is the problem with heating large houses it would be good to know that as well.

All advice and opinions would be welcomed and appreciated

dpofloinn · 05-02-2014 3:37pm

Your rads could be under sized .Could you post a little more information like make and model of your boiler and output,size of rads for example 1200 long single panel or double.How many windows and their type ie double glaze,triple glaze etc,level/standard of insulation,how many rooms with external walls,how many rads.Is the system zoned,trvs,do you use the boiler to heat water.If you feel like doing the maths yourself try using this calculator http://www.homesupply.co.uk/radiator_output_calculator.php

Wearb · 05-02-2014 5:10pm

Det Somerset wrote: »

I posted a different but closely related query elsewhere on Boards yesterday, but thought this question would be more suited to a new thread in this sub-forum. Apologies if this was the wrong approach to take.

I bought a large 2500 sq ft bungalow last year. It was an old house and had been unoccupied for maybe 3-5 years. I had major renovations done to it, including a new heating system and radiators and as much extra insulation as I could afford. Since we moved in before Xmas, we have been using the heating very sparingly as we couldn't afford to fill the oil tank significantly at the time. Over the last week or so, we have been trying to heat up the house more suitably and have found that the natural 'cold' temperature of the house is around 12 degrees and if we have the heating on for 4 hrs straight the temperature rises to about 17 degrees, so it seems that we get a rise of just over a degree an hour with the heating on. I would have thought this to be slow and possibly insufficient but I'm not an expert so would appreciate some opinions on whether that is normal for a house of this size or poor. There are three possible explanations that I can think of here ...

1. As has been explained to me by both the builders and another helpful poster on Boards, the floor slab and walls of such a property would still be damp and as a result the rooms will be naturally colder and probably slower to heat, which is what I'm experiencing now but this will improve suitably over time.
2. I've gone from a standard 3 bed semi which heated up a lot quicker, to a sprawling large roomed bungalow with a number of high ceilings which just takes a lot longer to heat and I'm foolish to think it will heat any faster.
3. The radiators are not suitable to heat the size of rooms we have and should be replaced.

As additional information, the radiators seem to reach close to full temperature after about 20 mins of turning on, they are then too hot to keep hold of so it's not that they aren't heating sufficiently. Due to the renovation costs rising far above our budget, we can't currently afford to burn oil endlessly to heat the house just for comfort. That said, if we could be certain that doing so for a day or two would dry the house out and then make it easier to heat going forward, we'd do that. Or, if it was felt here that the radiators sound like they are insufficient, now would be the time to talk to the builders about that as they are still finishing off snags. But if we just need to accept that this is the problem with heating large houses it would be good to know that as well.

All advice and opinions would be welcomed and appreciated

When you say that your rads are too hot to keep hold of, is that all over, especially the bottom centre of the rad?

Det Somerset · 05-02-2014 5:44pm

I'm currently at work and will be visiting my mother tonight. I'll take a look at the rads tomorrow night and respond to the questions then.

Det Somerset · 07-02-2014 1:17pm

Ok, here's some additional information although I didn't have time to measure/assess all the rooms.

Make/Model of boiler: Yet to be determined. It's an external boiler and it was too cold and dark last night to check!
System has two zones, one for rads and other for water. We only ever turn on the water for an hour a night.
Rads all have TRVs apart from the room with the thermostat as you would expect. We leave them fully open apart from the few rooms that are currently just used for storage.
All windows are PVC double glazed although some are older than others.
Attic space has that rolled out insulation and the external block walls have been pumped with insulation although that was done before I purchased it so I can't be sure of the quality.
Ceilings are higher than average at 2.5 metres.
Rads are too hot to hold at top and centre but just about possible to hold at the bottom despite being very hot

I used the recommended calculator to assess 2 rooms last night. The main bedroom which is the coldest room and the one I have the most problems with, and another bedroom that is being used as a home office which has only been lightly used so far, but definitely seems to heat up better.

Office: One External Wall (With external insulation). One window. Laminate over concrete floor. Calculator suggests 742 watts and a btu of 2532

Bedroom: Two external Walls (one with external insulation, one without) Two windows. Laminate over concrete floor. Calculator suggests 1346 watts and a btu of 4592.

Rads: Both are same type, 50mm deep, 500mm high, with the sole difference being the office one is 1300 long and the bedroom 1400mm. I believe they are single panel with fins (forgive my ignorance if this is incorrect, but there is the solid panel at the front where the water flows and wall side are vertical thin waves which I presume are fins) I used the method explained here ... http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=8021 to try and estimate the BTU of my existing rads and found that the office one is 3819 which would appear to be suitable, but the bedroom one is 4113 which seems to be too low for the room based on my layman's calculations.

Some further information. When we return in the evening both the bedroom and kitchen (where we have thermometers currently) are about 12.5 degrees. If we have the heating on for 3 hrs, the temperature rises to around 16 degrees. We have an electric 2Kw dimplex convection heater on a timer in the bedroom. It's on for an hour before we get up at 7am to take the chill out of the room. Nowadays, when we wake the bedroom is 16 degrees after that one hour, whereas the kitchen unheated is back to 12 degrees. I can't be certain yet but the impression I get is that the bedroom would also be 12 degrees or close to it, but the electric heater lifts the temperature a good 3 or 4 degrees in one hour as opposed to the 3+ hrs it takes the rad.

All signs pointing to the radiator being insufficient? How long should it take a rad to heat a room?

MicktheMan · 07-02-2014 3:04pm

Det Somerset wrote: »

Some further information. When we return in the evening both the bedroom and kitchen (where we have thermometers currently) are about 12.5 degrees. If we have the heating on for 3 hrs, the temperature rises to around 16 degrees. We have an electric 2Kw dimplex convection heater on a timer in the bedroom. It's on for an hour before we get up at 7am to take the chill out of the room. Nowadays, when we wake the bedroom is 16 degrees after that one hour, whereas the kitchen unheated is back to 12 degrees. I can't be certain yet but the impression I get is that the bedroom would also be 12 degrees or close to it, but the electric heater lifts the temperature a good 3 or 4 degrees in one hour as opposed to the 3+ hrs it takes the rad.

All signs pointing to the radiator being insufficient? How long should it take a rad to heat a room?

Clearly, something's wrong. I'd be concerned as to why the temp drops to such low levels in the first place, regardless of rad sizing. Have you had or considered having a full heat loss survey done to ascertain the main heat loss mechanism(s)?

Det Somerset · 07-02-2014 3:32pm

MicktheMan wrote: »

Clearly, something's wrong. I'd be concerned as to why the temp drops to such low levels in the first place, regardless of rad sizing. Have you had or considered having a full heat loss survey done to ascertain the main heat loss mechanism(s)?

I fully appreciate your logic, but we couldn't afford the assessment let alone any additional work for the next 6 months anyway. I would just like to understand if the rads are unsuitable as it would mean I could in theory demand the builders do something about it at their expense as we didn't pay them to put in a heating system that doesn't heat the house like it should. Having never lived in a spacious bungalow, I don't know what realistic expectations I should have in terms of heating the place.

Det Somerset · 07-02-2014 3:45pm

MicktheMan wrote: »

Clearly, something's wrong. I'd be concerned as to why the temp drops to such low levels in the first place, regardless of rad sizing. Have you had or considered having a full heat loss survey done to ascertain the main heat loss mechanism(s)?

Oh and I've been told that our current house temperature is lower than normal due to the house having been unoccupied for years and the roof having been off and walls demolished during the renovation. The indication given to me is that the fabrics of the house are cold and damp and will take time to heat up and that next year will see a difference. I'm prepared to accept that but I just want to know why we can't seem to heat the house up quickly with our heating system.

dpofloinn · 07-02-2014 4:01pm

A few more questions was the heating upgraded or significantly altered during the renovation?Did you eliminate a number of rads ?Do you have open firelaces that are not used? Do you heat all the rooms or just some of them?.Do you have open wall vents in your rooms?

MicktheMan · 07-02-2014 4:06pm

Det Somerset wrote: »

I would just like to understand if the rads are unsuitable as it would mean I could in theory demand the builders do something about it at their expense as we didn't pay them to put in a heating system that doesn't heat the house like it should. Having never lived in a spacious bungalow, I don't know what realistic expectations I should have in terms of heating the place.

Going after the builders wrt the rads/heating system may not be worth it if there are significant heal loss issues in the house to begin with.
As an example:
I bought a bungalow in 2003, originally built 1977. The house wouldn't heat past 17/18 degC even with heating on 24/7. We got a builder to address the main heat loss weaknesses the following year. The next winter the house heats up in no time and retains it's heat for hours. We didn't change the insulation to any great extent nor the heating system.

Det Somerset wrote: »

Oh and I've been told that our current house temperature is lower than normal due to the house having been unoccupied for years and the roof having been off and walls demolished during the renovation. The indication given to me is that the fabrics of the house are cold and damp and will take time to heat up and that next year will see a difference. I'm prepared to accept that but I just want to know why we can't seem to heat the house up quickly with our heating system.

Living in a newly built/renovated house will cost more to heat for the first heating season (due to the structure having to dry out) but should still heat up. Just because the house was empty or had its hat off for a while has little to do with your issue, imo.

Det Somerset · 07-02-2014 4:21pm

dpofloinn wrote: »

A few more questions was the heating upgraded or significantly altered during the renovation?Did you eliminate a number of rads ?Do you have open firelaces that are not used? Do you heat all the rooms or just some of them?.Do you have open wall vents in your rooms?

Heating system completely replaced apart from reusing some of the existing pipes, but new boiler and new rads.

Two open fireplaces originally. We removed one entirely and the other is now sealed off with a wood burning stove.

Sometimes we heat all the rooms, sometimes just the ones in use. It doesn't seem to have any effect on heat either way.

Open wall vents were put in recently but again we haven't noticed any great difference pre or post install.

Det Somerset · 07-02-2014 4:31pm

MicktheMan wrote: »

Going after the builders wrt the rads/heating system may not be worth it if there are significant heal loss issues in the house to begin with.
As an example:
I bought a bungalow in 2003, originally built 1977. The house wouldn't heat past 17/18 degC even with heating on 24/7. We got a builder to address the main heat loss weaknesses the following year. The next winter the house heats up in no time and retains it's heat for hours. We didn't change the insulation to any great extent nor the heating system.

Living in a newly built/renovated house will cost more to heat for the first heating season (due to the structure having to dry out) but should still heat up. Just because the house was empty or had its hat off for a while has little to do with your issue, imo.

The thing is the builders supposedly specialise in heating systems and insulation so I would have expected they would have addressed any obvious heat loss weaknesses as it was their instruction to do so from day one. I appreciate what you are saying though. I would have equally expected them to install suitable rads, so something definitely isn't right. At least the opinion here is seemingly enough to suggest I can say this to them without looking foolish.

dpofloinn · 07-02-2014 4:46pm

One last question do you have curtains that overhang the radiators

MicktheMan · 07-02-2014 4:54pm

Det Somerset wrote: »

The thing is
1.the builders supposedly specialise in heating systems and insulation
2.so I would have expected they would have addressed any obvious heat loss weaknesses as it was their instruction to do so from day one.
3.I would have equally expected them to install suitable rads, so something definitely isn't right.
4.At least the opinion here is seemingly enough to suggest I can say this to them without looking foolish.

1. They probably do and may have done a good job wrt heating / insulation. But remember insulation doesn't, on its own, address all heat loss mechanisms!
2. What was their instruction exactly and who gave it. Was these a professional involved such as an architect, engineer, energy / heat loss consultant?
3. They may well have installed suitable rads / system.
4. This wouldn't be my opinion until the nature of the heat loss has been established.

Det Somerset · 07-02-2014 10:17pm

dpofloinn wrote: »

One last question do you have curtains that overhang the radiators

Yes but only when they are off. We literally roll them up onto the windowsill when the rads are on to make sure the heat isn't blocked. We'll shorten them in time but for now that's our method.

Det Somerset · 07-02-2014 10:27pm

MicktheMan wrote: »

1. They probably do and may have done a good job wrt heating / insulation. But remember insulation doesn't, on its own, address all heat loss mechanisms!
2. What was their instruction exactly and who gave it. Was these a professional involved such as an architect, engineer, energy / heat loss consultant?
3. They may well have installed suitable rads / system.
4. This wouldn't be my opinion until the nature of the heat loss has been established.

1. Fair point
2. I may have given the wrong impression here, but what I meant to say was I myself asked them to assess the existing house and recommend all that was necessary to result in a warm insulated house, ie replace any rads or windows that needed replacing etc. The answer I got was that they would take care of all that.
3. Quite possibly. I accept that as I'm not an expert.
4. Fair comment and I respect your opinion here. I still currently think there is enough evidence (maybe I'm indirectly aware of more than you at this point) to question the suitability of the rads. The main argument I would point towards is that the standard electric heater seems to heat the room more easily than the radiator does. If it was a heat loss issue and the radiators were fine, I don't see how the electric heater would be able to do the job (heat the room) and the radiators couldn't. I'm just logically minded so that's what makes sense to me here but again I'm not trying to say I know more than others who know more than me in this area.

esox28 · 07-02-2014 10:28pm

What was your before and after ber?

what depth insulation is in attic space?

Did you address air tightness during renovation?

Apologises for all the q's

Det Somerset · 07-02-2014 10:35pm

esox28 wrote: »

What was your before and after ber?

what depth insulation is in attic space?

Very good questions but the only one I know the answer to is that the 'before' BER was an 'F' rating. The builders expected to bring that up to maybe a C3 but I never actually got a confirmation when they were done. Will try and seek this out next week.

Don't know the specific depth insulation either. Might try go take a look tomorrow.

Sorry I couldn't provide better answers to help your assessment

timmy4u2 · 07-02-2014 10:48pm

Det Somerset wrote: »

Very good questions but the only one I know the answer to is that the 'before' BER was an 'F' rating. The builders expected to bring that up to maybe a C3 but I never actually got a confirmation when they were done. Will try and seek this out next week.

Don't know the specific depth insulation either. Might try go take a look tomorrow.

Sorry I couldn't provide better answers to help your assessment

Well your rads are heating up as well as they can so the problem is not with your heating system as such.
Are your rads of a poor design in that they are not dissipating the heat as well as you would expect them to? Or are they just too small.
I had state of the art alurad aluminium radiators in my house, bought several years ago at a considerable cost over steel rads.
Heating was adequate but not sufficient.
Last october I fitted solo rads in the hallway, landing and five other rooms and the difference is unbelievable.
This winter our quality of heating is far superior to last year and the heating is on on average three hours a day longer.
Our fuel bill to date has decreased by 21% on last year and our electricity bill is down 28.2% on the same period last year.

Det Somerset · 07-02-2014 11:02pm

timmy4u2 wrote: »

Well your rads are heating up as well as they can so the problem is not with your heating system as such.
Are your rads of a poor design in that they are not disapating the heat as well as you would expect them to? Or are they just too small.
I had state of the art alurad aluminium radiators in my house, bought several years ago at a considerable cost over steel rads.
Heating was adequate but not sufficient.
Last october I fitted solo rads in the hallway, landing and five other rooms and the difference is unbelievable.
This winter our quality of heating is far superior to last year and the heating is on on average three hours a day longer.
Our fuel bill to date has decreased by 21% on last year and our electricity bill is down 28.2% on the same period last year.

My layman's gut feeling is that the rads aren't suitable for some reason ... size ... design ... material ... placement ... who knows, but it would make sense if it was them. Am seriously leaning towards discussing them with the builders and challenge them (non aggressively) to explain how they are suitable given the situation and concerns I have. I feared asking the question on here might result in an avalanche of replies stating that's just how it goes in a spacious bungalow and I was a fool to think it would be different. The lack of that means there's something not right so it's up to the builders to defend their work with suitable explanation for what we are experiencing.

timmy4u2 · 07-02-2014 11:40pm

Det Somerset wrote: »

My layman's gut feeling is that the rads aren't suitable for some reason ... size ... design ... material ... placement ... who knows, but it would make sense if it was them. Am seriously leaning towards discussing them with the builders and challenge them (non aggressively) to explain how they are suitable given the situation and concerns I have. I feared asking the question on here might result in an avalanche of replies stating that's just how it goes in a spacious bungalow and I was a fool to think it would be different. The lack of that means there's something not right so it's up to the builders to defend their work with suitable explanation for what we are experiencing.

Well they are heating up well but obviously are not transferring the heat.

As the recommended amount of Solo Rads on one run is seven I have retained some of the alurad rads until I alter the system this summer.
When the alurads go below 55 they really do not heat the room whereas the Solo rads will keep blowing out the heat down to 38.
I think the design of the Rad is very important and the more fins the better the convection.

a common house radiator. Its design is such as to maximize the contact surface between air and the radiator body. Hence the thin and numerous fins.

(i) Conduction is a direct-contact transfer of heat from a region of higher temperature to a region of lower temperature. Your radiator is hot, so it heats air which surrounds it because the air is colder. The air is in contact with radiator surface, and the radiator is designed so as to have a maximum contact surface to transfer heat more efficiently.

Heat energy in a gas is, actually, in the speed the gas molecules move around: the hotter the gas is (the more heat there is), the faster its particles move. The total kinetic energy of its particles is the total heat in it. When hotter gas comes in contact with a colder one, the faster molecules collide with the slower, and they lose speed, while the slower ones gain speed. Thus, they lose kinetic energy (Ek=m*v^2/2), which the slower ones get. Macroscopically, the hot gas cools down, while the cold gas heats up.

In solids and in liquids, the situatuon is more complicated. For example, in metals, there are atoms in crystal structures, and they do not move around freely, but rather they oscillate around fixed positions. The more vigorously they oscillate, the more energy they have, the hotter the metal (more heat). If the metal is heated too much, the atoms oscillate too vigorously to stay at their fixed positions, they leave those positions and the structure break downs: the metal melts and turns into a liquid.

In essence, the metal radiator surface transfers heat from its atoms to surrounding air molecules by physical contact. The heats is conducted from metal radiator to the air in contact with it. This is conduction.

(ii) Convection, in this case, works like this. The radiator fins are vertical. They heat the air in contact with the metal fin surface. The air becomes hotter, it expands, and becomes lighter. So it goes upwards (like in a fire, when the air heats up, it runs upwards so the flames are always oriented upwards and the gases run upwards). When the heated air goes upwards, it carries heat away from the radiator. The cold air at the bottom, under the radiator, is sucked between the vertical fins, and is now heated, goes up etc. The hot air in the room loses heat to other objects, cools down and falls to the bottom of the room just to be re-sucked between the fins, reheated, and this goes on, and on. The air thus circulates. This is known as free or natural convective heat transfer.

(iii) Radiation. Well, any object at any temperature emits radiation, as described by the Stefan-Boltzmann law. The emitted energy is proportional to T^4 (T=temperature). As the surface temperature rises, obviously, the more radiation leaves that surface. Since the radiator surface has a higher temperature than its surroundings (the walls and objects in the room, that also radiate heat), it radiates more heat away, than it receives from the surroundings. Actually, radiative heat exchange happens all the time, between all the objects everywhere. The radiator loses much more heat, since T^4 rises quickly as T rises. Therefore, the net effect is that it loses heat to objects and walls in the room. It, thus, also heats the room by radiation.

Is my new heating system working suitably?

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