Underfloor Heating Reccomendations
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So many installations never had the insulation fitted, it is hard to tell which are good and which are bad, but the major problem is control, my old house worked, so it all seemed simple, until I returned to mothers house, and realised her problem was speed, the heating took too long to react to changing conditions, bay window and sun was her problem, as soon as the sun hit the bay window the room temperature started to raise, so wanted the radiator to turn off fast.
My point is what works great in one home, may not work in another, reaction time is not some thing that jumps to mind when designing central heating, and when you say "Boiler or Air Source heat pump?" if using same fuel then the air source heat pump is likely best, but why use an air source heat pump with UFH? The whole advantage with air source heat pump is it can heat or cool, so fan assisted radiators are the way to go.
If using a different fuel, what fuel? Oil boilers are more expensive to gas, and are off/on, where a gas boiler modulates, so seems likely UFH will work better with gas than oil. Theory my oil boiler should alter the mark/space ratio and gradually adjust to heating requirements, but in practice it over shoots, so we get a hysteresis in temperature. Where gas boilers reduce the temperature of the circulating water, so less likely to over shoot, but when used with UFH the temperature is reduced further, and reaction time is increased, so normally one has a combination with a fan assisted radiator which has a very fast reaction time to counter the super slow reaction time of the UFH.
To my mind an engineer is qualified to degree standard and a tradesman to collage standard, and to work out how to install and set up UFH needs an engineer, some times people are lucky, but the control of UFH has to be right first time, you can't easy replace it with a bigger radiator because that room is cold, so you need some one who specialises and can get it right first time.
My point is what works great in one home, may not work in another, reaction time is not some thing that jumps to mind when designing central heating, and when you say "Boiler or Air Source heat pump?" if using same fuel then the air source heat pump is likely best, but why use an air source heat pump with UFH? The whole advantage with air source heat pump is it can heat or cool, so fan assisted radiators are the way to go.
If using a different fuel, what fuel? Oil boilers are more expensive to gas, and are off/on, where a gas boiler modulates, so seems likely UFH will work better with gas than oil. Theory my oil boiler should alter the mark/space ratio and gradually adjust to heating requirements, but in practice it over shoots, so we get a hysteresis in temperature. Where gas boilers reduce the temperature of the circulating water, so less likely to over shoot, but when used with UFH the temperature is reduced further, and reaction time is increased, so normally one has a combination with a fan assisted radiator which has a very fast reaction time to counter the super slow reaction time of the UFH.
To my mind an engineer is qualified to degree standard and a tradesman to collage standard, and to work out how to install and set up UFH needs an engineer, some times people are lucky, but the control of UFH has to be right first time, you can't easy replace it with a bigger radiator because that room is cold, so you need some one who specialises and can get it right first time.
Eric, I thing you're confusing tradesmen with interior designers, though I do enjoy reading your verbose posts
Not so, a skilled trademan with the required competence and experience will do, just as you don't need a surgeon to administer a vaccine. It's been a bugbear of mine since GSR was formed, they insist on calling Gas fitters 'Engineers', and some believe they are.
No, no, no, it's important that the design and installation (of the UFH pipework) is right first time. The controls are easily re-parametised and tuned to provide an acceptable quality of comfort.
There is no technical reason why you can't have an air source heat pump (ASHP) and a small gas boiler for supplemental heat. ASHPs are great in the summer, not so good in the depths of winter when you want more heat. ASHPs are expensive, even more so when they go wrong, when compared to gas boiler parts (hard to believe, knowing most gas boiler spares' prices!). ASHP will NOT give you adequate hot water in the winter, for the reasons given above.
Oh, and the electricity to run them costs about 4 times as much as gas, so they're really not much cheaper to run at current energy prices.
I hope this helps...
MM
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@MeldrewsMate is correct, a heat pump can raise or lower the temperature by 40°C as we see with a domestic freezer, but we want DHW at +65°C to protect from legionnaires so it is pushing them to the limit in the winter. But you have not talked about heating domestic hot water, and you don't want the floor to exceed 30°C or one would have a problem walking on it with bare feet.
And yes if a doctor has seen a some one and decided they need weighting or an injection then they can pass the work on to people trained to a lesser extent, and in the same way engineers will assess what work can be passed to tradesmen or mates.
But when I went to my mothers house, which had the whole system renewed, and a combi boiler installed, by a so called specialist firm, it was to put it mildly a mess, in the main lack of commissioning, but when I came to try and improve the system it was not as easy as I thought, I tried wall thermostats, and programmable TRV heads all improved it but still not good enough, the cure was adding a TRV head to hall radiator where the wall thermostat was, which was against every recommendation I had read, they all said do not fit a TRV in same room as wall thermostat, but in mothers house it worked.
In my trade/profession I have walked into a situation and like Miss Marple who done it, I realise I have seen some thing similar in the past and can dispense with a load of calculations and simple inspect and test on completion, very few times do I need to sit down with the slide rule and work it all out. But some I realise it is going to be on the edge, so it is a case of working it out first, and deciding if it will work.
Some tradesmen are very good, others are to be frank are little better than a mate. The we do it this way, why? because we have always done it this way. So with an extractor fan 85 m³/h in a bathroom the heating must replace that heat, it does not take that much to realise a 300 watt electric UFH is not going to replace the heat being blown outside, without the extractor it may have a chance, or with a heat recovery unit, or if it was getting replacement air from some room already hot, but from the cool hall no chance, and to be frank had it been more than 300 watt would have been no better as floor about as warm as one would want it to walk on.
The 30°C limit means UFH takes a long time to get rooms warm, in the main today we look at less than an hour to warm a room, so in the main looking at a hybrid system to get fast warm up. Of course some premises care homes for example are never allowed to cool, and having no radiators for wheel chairs to hit or people to lean on is an advantage. But in my house I want it cool at night.
And yes if a doctor has seen a some one and decided they need weighting or an injection then they can pass the work on to people trained to a lesser extent, and in the same way engineers will assess what work can be passed to tradesmen or mates.
But when I went to my mothers house, which had the whole system renewed, and a combi boiler installed, by a so called specialist firm, it was to put it mildly a mess, in the main lack of commissioning, but when I came to try and improve the system it was not as easy as I thought, I tried wall thermostats, and programmable TRV heads all improved it but still not good enough, the cure was adding a TRV head to hall radiator where the wall thermostat was, which was against every recommendation I had read, they all said do not fit a TRV in same room as wall thermostat, but in mothers house it worked.
In my trade/profession I have walked into a situation and like Miss Marple who done it, I realise I have seen some thing similar in the past and can dispense with a load of calculations and simple inspect and test on completion, very few times do I need to sit down with the slide rule and work it all out. But some I realise it is going to be on the edge, so it is a case of working it out first, and deciding if it will work.
Some tradesmen are very good, others are to be frank are little better than a mate. The we do it this way, why? because we have always done it this way. So with an extractor fan 85 m³/h in a bathroom the heating must replace that heat, it does not take that much to realise a 300 watt electric UFH is not going to replace the heat being blown outside, without the extractor it may have a chance, or with a heat recovery unit, or if it was getting replacement air from some room already hot, but from the cool hall no chance, and to be frank had it been more than 300 watt would have been no better as floor about as warm as one would want it to walk on.
The 30°C limit means UFH takes a long time to get rooms warm, in the main today we look at less than an hour to warm a room, so in the main looking at a hybrid system to get fast warm up. Of course some premises care homes for example are never allowed to cool, and having no radiators for wheel chairs to hit or people to lean on is an advantage. But in my house I want it cool at night.
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If you are still looking for options of your underfloor heating, feel free to drop me an email with your floorplans and floor build up and I'll get something worked out for you: ###############
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