Warm Air Heating v/s Wet Radiator Heating

[Mikefromlondon]

I am in a position to verify or conduct a little test to determine which one was or is better, I have a Warm Air Heating in a house that I feel was more efficient even though the applaince is 25+ years old, (Johnson & Starley) and as soon as you put the heating on, the house seemed to get warmed very very quickly, but how much gas it used I don't know.

So now I have also got a new central heating installed, with 7 rads and 5 rads fitted with TRVs, with an Ideal Mini-i 24 combi boiler all installed in one and half days and cost 3K, complete installation. Flue with 2 90 deg bends and total run of no more than 2 meters.

Now I would like to see how efficient or inefficient Warm Air Unit was, already I have a feeling that the enw heating isn't as effective despite running it for an hour, used almost 1 cu m of gas, and the rise in temperature was only 4 degrees Celcius.

All rads were sized and look proportionally sized for each room, all are single and high radiant rads. One room (box room had a 1000mm rad that seemed to be overkill and reached a temperature of 24 deg celcius, but overall all other rooms were at 18 C from 14 C after an hour,

I need to device a method to compare the two, how do I do?

Do I base it on the same amount of gas used by each heating system and then measure the overall rise in temperature?

Or Do I run each for an hour and then measure the rise in temperature and take the amount of gas used by each system?

This is just for a personal satisfaction and to break any myths that modern gas combi boilers are more efficient, so I wanted to find out how much more efficeint they are and in how many years will I recover my 3K I laid in the name of efficiency and lower running costs. thats the million dollar question, was it worth it?

As for noise, both are noiesy and as the fan on both systems conduct its noise throughout the quiet house may be a decible more on the WAU.

As for safety both are just as criticle, for vulnerability to CO leakage as there is an internal 2m run of the flue on the new one, as opposed to punctured heat excahnger on the WAU due to rust of corrosion, and the efficiency measures will be like for like as far as the insulation or heat loss is concerned.

 

[footprints]

Did your warm air provide hot water?
At best it had a gas circulator that took an hour or so to heat or perhaps an electric heater, not really a simple comparason with your new combi

 

[Dan Robinson]

If you think an Open Flued Warm Air unit is as safe as a room sealed combination boiler (installed correctly) then you are barking - or in your case meowing.


If you do in fact carry out a fair and accurate assessment I am sure we will all be interested in the results.

See - I can be civil when the mood takes me.

 

[Mikefromlondon]

Did your warm air provide hot water?
At best it had a gas circulator that took an hour or so to heat or perhaps an electric heater, not really a simple comparason with your new combi

Yes it once did have the cicular gas water heater, that was decommissioned years ago and the hot water was then supplied by an electric emersion heater.

But I am only comparing heating efficiency, of course warm air will heat the house quickly as it is forced flow of heated air, so likewise it would probably cool off just as quickly unless the heating was on for a considerable time and the heat was absorbed by furnishings and walls, to provide after glow like heat effect, so I will probably take another temperature after the heating gets switched off to see how the room temperature falls to degree celcious after say another hour, that would be more fairer, since rads will still be warm for a considerable more time after the heating is switched off and would continue to radiate heat for some time longer.

 

[Mikefromlondon]

If you think an Open Flued Warm Air unit is as safe as a room sealed combination boiler (installed correctly) then you are barking - or in your case meowing.


If you do in fact carry out a fair and accurate assessment I am sure we will all be interested in the results.

See - I can be civil when the mood takes me.

No I am not barking or whatever, meowing or crying like a baby!

but I have learnt through sensible discussions on other forums why Warm Air Units are more critical because in a room sealed unit, the system draws its own fresh air supply (oxygen) and in an open flue systems, a negative pressure can draw exhaust gasses including the lethal CO and other gasses back in and can also cause a flame reversal, on top o0f this depletes oxygen levels and that can cause improper combustion emitting more CO and other noxious products.

usually happens when the householder blocks permanent vents, which actually did happen in this house, or adds a powerfull extractor fans in bath or kitchen, which could prove lethal, but on top of this the main reason being if the dry heat exchanger had ruptured through corrosion or rust, then the lethal gasses can escape into the warm air supply and feed into all rooms, and kill occupants, whereas, in a sealed applaince even if the heat exchanger had gone wrong and its combustion chamber walls had developed leaks then escaping lethal gasses are within the casing of the unit and there is lower leakage to the surrounding area, other than if there was a serious fault in the joints and couplings of the flue or its overall condition.

However, having said that, why i think even some older room sealed applainces were just as bad as the warm air units, because my Vaillant VCW221 had developed a fault with its lower heat excahnger, this sits under the main heat excahnger and has a copper surround with water pipes running all around this body before going into the main heat exchanger on top, this copper skirting or walls had corroded away or simply burnt off over years of use, so then some of the flames started to emerge from the sides instead of going straight up into the flue, and these flames escaping from the sides caused a plastic cover on the top to melt, and as well as discharge CO, luckily I had bought a new CO detector a few months earlier and it went off, this gave rise to my concern and I called my RGI mate who checked and found that my lower heat excahnger had deteririorated rapidly as during his last service call there was no such signs of deterioration.

He thinks it may have deteriorated rapidly due to my running the boiler/heating at lowest flow temperature, this can cause less heat to allow air to circulate naturally due to convection flow, hot air is lighter and so rises , or due to density differntial, as this boiler flue is not fan assisted, and so running it on lowest flames, the overall temperature of the combustion means vulnerability to condensate, which may have cause this corrosion as the copper skirting had gone green with corrosion and burnt in several places, so whenever the boiler was on full power i.e. during hot water demand, flames started to seep out from the sides, and caused palstic cover on top to melt, and also set my CO detector off, luckily I only bought this CO detector because I bought one for my WAU, and Iliked it so much and I thought another one for my house, at just over £24.00 it was well worth it with a digital read out! It gives PPM readout as opposed to just an alarm, my boiler set it off at 330PPM!

However, I say it was condensate but if there was real water leak, I would have noticed it much earlier as the sysetm would be loosing water pressure, but the system had no loss of water pressure, and did not require toopping up, so it must have been condensate to have cause this corrosion.

since this incident, I now try and avoid running it at such low flow temperatures, 50 C minimum is reccomended by my mate.

 

[Mikefromlondon]

Of course I forgot to add, the pilot flame on my WAU consumes gas which is the biggest draw back, so it is the negative aspect to WAU, or any other older systems including my vaillant VCW221, how much per day the pilots consume, I will have to find out the true cost of this as well.

The RGI guy who did my new heating installation estimates that it must cost me al least a pound a day to run that pilot every 24 hours! will see exactly how much it costs, luckily the gas meter is a prepayment meter and displays the amount used, including standing charge .

BTW, the warm air heating will be decommissioned soon, but I told him to leave it running for now as I wanted to compare out of interst. That was also included in his price, along with registering the job with Gas safe, and the local council building control and issuing a safety certificate.

 

[Agile]

Pilot is about £30 per annum.

During the winter that's useful heat!

Tony

 

[Mikefromlondon]

Pilot is about £30 per annum.

During the winter that's useful heat!

Tony

Thats not too bad then, I did think the Engineer was exaggerating how much it did cost in order to tip my decision once and for all to go for the new wet system using a condensing boiler.

However the only reason to tip my decision in favour of a room sealed combi boiler replacing otherwise well serviced WAU was that as a Landlord you cannot trust your tenants to adhere to strict rules regarding permanent vents, last year this lady she not only blocked all PV with a duct tape, but also stuffed padded jackets in the ducts which feed warm air to rooms upstairs, even though the registers or grills had the facilities to regulate direction and flow rate but she wanted to seal them completely air tight so as to save on her heating fuel bills, as she spent most of her time downstairs, she did not want upstairs rooms heated , so she stuffs the duct work, this caused built up of heat in the WAU cupbaord and melted the thermoplastic front panel cover of my WAU as well as I don't doubt some flame reversal may have occured due to blocked PV, where the heat from the flames poking out from the burner reached directly towards the front panel.

She also diced with death along with the lives of her two little children, when this WAU front panel melted, she knew what she had done (stuffing the ducts and blocking the permanent wents) so she did not report its failure to me, and started to use portable calor gas heatingn instead, still with all vents closed off!

As a landlord I was highly vulnerable to being prosecuted and even jailed should any mishap happened, or loss of lives through a faulty heating applaince, even though caused by tenants themselves through interfereing with heating applainces, it would be hard for me to prove who tampered, and the tenant wouldn't admit and all the blame could fall squarely on me, hence this is what made me go for the new wet heating system with less vulnerability to tampering by any future tenants, particularly the issues with vents that can be blocked easily by most tenants.

Even though last year I spent over 300 quid on new parts, to have that WAU overhauled, replaced all its sensors, regardless if they were faulty or not, replaced the gas valve, except the heat exchanger, that was inspected visually with light for any puncture or other imperfections, made out of stainless steel, it was found to be in a perfect condition, as it was replaced about 10 years ago, ( the same guy/company who did my new installation did thsi overhaul) and a new steel front panel, shame that is all now gone to waste! and not forgetting the 200 quid labour charge I paid to restore that WAU.

The tenant was given a written warning not to block any more PV or tamper with Duct work, and to stop using any portable gas applainces as my house insurance did not cover them against any risk. thats tenant s for you and she also destroyed most of my house, ruined a nice well kept garden ! this biatch was definitely a tenant from hell!

 

[Mikefromlondon]

Oh well, I think there may be some problem with my New CH, hence why it seems to take ages to warm the place, this may be due to the TRVs, I have set them at maximum setting of 5, and the rads become very hot then go cold, according to the leaflet these TRV's can be fitted to either flow or return side, so the biggest room where one of them is fitted to 16m long rad the room temperature rose from 16C to around 18C in about 15minutes , I could feel the heat on my forehead in the middle of the room, but then and half hour later the room felt cold and the temperature went down to 17C, and the radiator was not even warm, felt more like it never came on! it seems the TRV has cut in even at its setting of 5, which I believe is the maximum setting, I could be wrong, now that all leaflets have been thrown away and I remember it said the temperature control range of the TRV is from 7C to 27C, I have no past experience with TRVs as my house does not use any, my system was done when TRV's weren't even on the drawing boards!

So I am going to contact my installer and ask him what make they were and see if I can find more about them, and why they seem to cut off preamaturely.

After running the heating for an hour, it had used just around 0.81 cu meters of gas, same as it did last time i ran it for an hour, hence why I said the old WAU seemed more effective, but it now seems there is a problem, one of you guys might know what it might be.

 

[Dan Robinson]

Budget boiler on budget controls poorly set up on incorrectly sized and balanced rads? (Delete as appropriate).

By budget read "crap".


A properly installed system won't do what you describe.

You may not like hearing this from me. But facts is facts dude.

 

[Agile]

Any professional installer would have been dealing with any problems and not leaving you to have to ask us here.

You seem to have very cheap TRVs which are turning off prematurely.

Good TRVs cost nearly £20 but the cheap ones are about £5. You get what you pay for. Both with TRVs and with installers!

I only fit Drayton or Danfoss TRVs! But then I don't work for many landlords because they want cheapness and not quality!

Tony

 

[Mikefromlondon]

Funny you should say this, I never haggled over prices, I asked my regular service engineer, and asked him to quote me for a complete wet heating system installed, except I asked him to allow no more than about £500.00 for the boiler, and this is where I suggested him to use like Biasi or Ideal or Main boiler, I did not want anything over priced boiler, and there it was, he asked for £2900.00 and I wrote him a cheque for £3,000.00, I never asked anyone else to give me another alternative quote.

The TRVs he used don't look cheap either, they look high quality, the Brand name is Bulldog, and are reversable, i.e. does not matter if you installed in flow or return path.

I have spoken to my installer, he said he would be more than happy to pop in when i am next at the property and he will check through for any problems, he has always used Bulldog TRVs and never had any problem from other installations, (PS The boiler was still on as the room state never reached the 20 deg C set temperature . Only the passage and the kitchen rads are fitted without TRVs. and the room state is mid way between these two rads if you leave the kitchen door open as it was.

I asked him if I could remove or unscrew the top wax module from the rest of the fitting and this should allow full flow through the rads, and see if this could determine the cause as a faulty wax module.

(Did I mention in one of my posts above that in a box room the temperature reached 24c in one hour when the TRV in that room was left at its Max setting (5) and the rad was still quite hot, I have no reason to believe that there may be any air trapped in the other room rad as initially it gets real hot and you can feel the heat rising as it strikes your forehead in the middle of the room, the flow temperature was around 70C at the boiler flow pipe as I measured that with my Multimeter Temperature Probe that uses a bead thermister and this is pretty accurate and quick to respond to changes in temperature.)

 

[Mikefromlondon]

Budget boiler on budget controls poorly set up on incorrectly sized and balanced rads? (Delete as appropriate).

By budget read "crap".


A properly installed system won't do what you describe.

You may not like hearing this from me. But facts is facts dude.

Your comments are not at all fair, but certainly one must look at the property value and area and crime rate in that area. this is a 3 bed mid terraced Ex Council property in Harlow in a Council Estate, and I wouldn't have bought a house here if it wasn't for my doing my Ex Boss a favour by buying it so as to break a housing chain, so that he could move out to a bigger and better detached house with a swimming pool!

Now what does that tell you? it tells you that before you can run you need to walk, or in other words, my Ex Boss who is probably now worth over 50Million once lived in this Ex Council Estate!

So today this property is worth no more than about 150K or there abouts, constructed of Concrete blocks, and very simple construction, why would I go out of my way to spend over 3K on a heating system, when the fact is this area attracts a lot of burgularies and benefit tenants, who don't know how to respect others property.

A while back (some years ago) my timber garden shed became a target of theives, two guys came in from the back access, and started to dismentle the then £200 B&Q garden shed 6'x4' and whilst the house was unoccupied, a neighbour chellenged the two lads and they fled leaving the shed in pieces almost ready to be carted away!

So whilst the house is again unoccupied and undergoing refurb or redecorating and cleaning up the mess the last tenant left it in , owing me more than 7K in rent, why would I want to install a good expensive heating system?

The Ideal Mini i 24 boiler is excellent and more than adequate for the job, I am sure the problem may only be the TRV, but will find out the cause next time I am in the area, this is retailed for about £750.00 at Plumb centre, but my local Vaillant Distributer who now also supplies other brands like Main or Ideal was offering the same boiler for £460.00 and a Main one for £485.00, but my installer gets his supplies from Plumb Centre.

But believe me your posts make Budget read crap!

 

[Dan Robinson]

Doesn't make then any less accurate though.

 

[Agile]

The Bulldog valves are not cheap, about £17 with a lockshield.

But its still a WAX element! They take three times as long to respond!

Made by Pegler which is normally a good maker.

This is like a budget specification at a quality price!