Sandybay Posted January 18, 2021 Share Posted January 18, 2021 Hi, Is it possible to run under floor heating system and hot water, from an oil boiler and what are the pros and cons versus Ashp to do the same? Link to comment Share on other sites More sharing options...
Carrerahill Posted January 18, 2021 Share Posted January 18, 2021 1 minute ago, Sandybay said: Hi, Is it possible to run under floor heating system and hot water, from an oil boiler and what are the pros and cons versus Ashp to do the same? Yes it is possible, holiday cottage we stay in every year uses an oil boiler and the whole cottage is UFH with tanked hot water. Personally if my options were limited to those two I would probably go oil for now knowing that one day I would need to change it - but lets face it, heating systems are like phones, you know you will need to one day. Link to comment Share on other sites More sharing options...
the_r_sole Posted January 18, 2021 Share Posted January 18, 2021 the thing that always gets me with a system like this is that you heat cold water up with the oil boiler and then mix it with cold water to circulate around the UFH, just seems wrong! The heatpumps are generally low temperature systems so they only heat the water to the point it needs to circulate in the heating system... Link to comment Share on other sites More sharing options...
Carrerahill Posted January 18, 2021 Share Posted January 18, 2021 13 minutes ago, the_r_sole said: the thing that always gets me with a system like this is that you heat cold water up with the oil boiler and then mix it with cold water to circulate around the UFH, just seems wrong! The heatpumps are generally low temperature systems so they only heat the water to the point it needs to circulate in the heating system... It does work this way but it is not like the heat is lost, for every litre of hot water, you might get 5 litres of warm water, the heat is going into the system, you cannot destroy the heat energy in the system, it gets used. It is a bit like a combi making hot water for a shower/bath/tap, to get a nice flowing shower I turn my hot on full and add cold to suit, I can turn my boiler down so I can use just hot water, but the flow is not as good because I don't have the benefit of some cold, so we have our boiler sitting at max DHW. Link to comment Share on other sites More sharing options...
the_r_sole Posted January 18, 2021 Share Posted January 18, 2021 2 minutes ago, Carrerahill said: It does work this way but it is not like the heat is lost, for every litre of hot water, you might get 5 litres of warm water, the heat is going into the system, you cannot destroy the heat energy in the system, it gets used. It is a bit like a combi making hot water for a shower/bath/tap, to get a nice flowing shower I turn my hot on full and add cold to suit, I can turn my boiler down so I can use just hot water, but the flow is not as good because I don't have the benefit of some cold, so we have our boiler sitting at max DHW. I know the principle - it just doesn't sit right with me for some reason! I think it's a combination of once living in a house which was oil heated and spending a lot of my days trying to get houses through building warrant in rural locations Link to comment Share on other sites More sharing options...
Sandybay Posted January 18, 2021 Author Share Posted January 18, 2021 Thanks both, Suppose looking into the future will probably go ashp, but good to know that can use oil boiler too. Link to comment Share on other sites More sharing options...
Temp Posted January 18, 2021 Share Posted January 18, 2021 (edited) 7 hours ago, Sandybay said: Hi, Is it possible to run under floor heating system and hot water, from an oil boiler and what are the pros and cons versus Ashp to do the same? We have an oil boiler that heats a thermal store (300L tank of water to) around 55C. A pump circulates water from the TS to the UFH manifolds. Pumps on the manifolds circulate the water around the floor loops. The thermal store also has a heat exchanger/coils in it. Cold water from the mains goes through the coil to mak the DHW which goes to showers and hot taps etc. The result is mains pressure hot and cold water everywhere. Well not exactly, on most taps we have pressure reducers/regulators to avoid water spraying all over the place. In addition to providing lashings of hot water the TS allows the burner in the boiler to run flat out without cycling on and off. Without a TS you can get a situation where only one or two rooms need heat. However the burner in an oil boiler cannot modulate down like a gas boiler so instead it has to switch on and off (cycle) to reduce its output to match demand. This is less efficient like stop start driving in a car. With a TS Basically the stat on the TS controls the boiler. When the TS calls for heat the burner runs flat out until the TS is satisfied. The TS then feeds whatever the UFH needs at the time. Its like driving at 56 mph all the time with fewer stops. As for running costs.. These depend on the heat loss from your house (which in turn depend on how well insulated and ventilated it is) and the DHW consumption. There are very few sources of data that compare the running costs of different fuels. The only one I know of is this one and its possible to argue with some of the assumptions they make. https://nottenergy.com/resources/energy-cost-comparison/ See the column headed "Pence per kWh (after boiler efficiency)" This takes into account the cost of electricity (at 19p/kWH), oil (29.4 p/L) and the COP of the ASHP (270). Kerosene 3.33 p/kWH Mains Gas Standard Rate 3.85 p/kWH ASHP 7.19 p/kWH On their figures oil is currently a lot cheaper to run and compares with mains gas. What do others pay for electricity at the moment? Edited January 18, 2021 by Temp Link to comment Share on other sites More sharing options...
Ronan 1 Posted January 18, 2021 Share Posted January 18, 2021 Hi Temp, that's interesting o plan to heat my new build with a oil burner as it's the predominant fuel type around me , never heard of the thermal store before but I really like the sound of it , I will have to do some research and talk to my plumber . Did it add much extra cost to the system ?? Link to comment Share on other sites More sharing options...
Sandybay Posted January 19, 2021 Author Share Posted January 19, 2021 Thanks Temp, Good to hear you can run a dual heating system from an oil boiler efficiently ? Link to comment Share on other sites More sharing options...
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