Great video as always

Always interesting videos that I do understand also

@andrewmillwardwatford9410

2 ай бұрын

I'm glad you said you understand them. Sometimes I imagine that people are watching these videos on thinking what the hell is he talking about talking about

A great simple explanation of WC ratio, i would point people doing the heat geek course this. When people say design rads and UFH to the same temp, its to lower temp. So if 40 max flow on ufh you size the rads to the same negating need for mixers.

@HowardBurgess

2 ай бұрын

That does make sense, but what concerns me is the difference in WC curve needed for the rads (e.g. 1.0) and the UFH (e.g. 0.5) If you upsize your rads to work at the UFH temperature, does that bring the required curves closer together? My understanding is not clear about whether that’s true or not. Or maybe, even though there is a difference in WC curve between the two types of emitter, it might work satisfactorily, even though it’s not perfect design.

@andrewmillwardwatford9410

2 ай бұрын

This seems to be a popular statement. Why would anyone design underfloor heating to run at such a high temperature?

@hiltonshaw5528

2 ай бұрын

@@HowardBurgess provided you’ve designed all rooms to the same temperature ie 21 degrees then the heat curves will be the same

@andrewmillwardwatford9410

2 ай бұрын

@@HowardBurgess an underfloor heating system running on a ratio of 1 is that the top end of underfloor heating design range. A radiator system running on a weather compensation ratio of 1 is also close to the Limit for radiators. In my opinion you'd have to design the underfloor heating to run poorly in order for it to run as hot as the radiators

@HowardBurgess

2 ай бұрын

@@hiltonshaw5528 you can size radiators and UFH to work at the same flow temperature for e.g. -2C outdoor and 21C indoor, but that’s just a single point. It doesn’t mean that the two emitters/rooms have the same curve. If they did, it would mean that as the weather became milder, the flow temperature for each was also in sync. However, it’s likely that in milder weather the UFH and radiators would need different flow temperatures, even if at design conditions they were equal.

I have two mixing valves on my Bosch heat pump. Each has a sensor seperately. I don’t have a buffer. I removed it and saved energy/costs. Both mixing valve units have its own pump for good delta t.

@andrewmillwardwatford9410

2 ай бұрын

You can't make the maths add up correctly for such a system design. You will have some interaction between the pump in the heat pump and the pumps in your mixed circuits. If you follow the calculations that I have done impossible to get a complete balanced answer. Like many systems that are not textbook installations the effects of the errors are often of little or no consequence and so go unnoticed. Some would argue that this means that the errors are ok but I would argue that this is not good design

@user-ju2mq6fp2e

2 ай бұрын

I thought I you keep the pumps and remove the buffer you will end having the heat pump pump and the mixer pumps hunting and will wear the plums causing premature failure.

@829001333

2 ай бұрын

Hi, have you measured compressor work aswell (in/out & length of active/working), with a buffer previously and without it later on?

@andrewmillwardwatford9410

2 ай бұрын

@@829001333 when you have a system with mixers it is an effect an open system as we have constant access to the water within the system and the mass of the screed if it's an underfloor heating circuit. On top of that we have the mass of water in the buffer. Because two mixed circuits cause the buffer to be required at very close to all the time the buffer water is added to the mix. This is advantageous for both reducing cycling and also for defrost.

@andrewmillwardwatford9410

2 ай бұрын

@@user-ju2mq6fp2e if the heat pump has certain sensors could be a fault induced by unwanted flow through the heat pump. The interaction of pumps could also cause the heat pump to struggle to maintain the correct delta t. But these flow differences could be very small if each of the mixed circuits runs on a very similar Curve. The point is that hydraulic separation ensures the system will operate correctly but without hydraulic separation we know that something will not be correct

Informataive as always, thanks Andrew. Liked and subscribed. In my situation I have UFH throughout a large, two storey, new build. With low flow temps in mind, pipes at 100mm c/c except bedrooms (150mm c/c). One manifold on each level. Ground floor slab is 100mm dense concrete with lighter cement screed upsatirs. Highly insulated & airtight house. I think my heat loss will be

@andrewmillwardwatford9410

2 ай бұрын

If a heating circuit requires a different flow temperature for it to operate correctly we use mixers to achieve this. If we are using mixers we will not be able to balance the mixed circuits with the flow rate at the heat pump and so we need hydraulic separation. This is provided by a buffer but it does not have to be a buffer and could just be a different form of hydraulic separation. Another reason for using hydraulic separation is when the pump in the heat pump does not have adequate residual pump head to produce the circulation required within the system and the heat pump when directly linked. If you are getting stable temperature throughout your home it is likely that you do not need either a buffer or hydraulic separation. If you are using on off thermostatic controls you might we'll find a buffer would benefit you.

@garethcranston1993

2 ай бұрын

@@andrewmillwardwatford9410 Thanks Andrew. Not moved in yet, so can't say. Haven't even bought the Heat Pump. I have space for a buffer and no issue with including, if of benefit. Like you though, have heard the same noise about it being of deteriment. I would have thought though, with the volume of water I have in the UFH, and the fact that I have no rads (other than towel rails off UFH manifolds), that if anyone can omit a buffer, it's me? I'm from a different engineering background and generally attracted to the simple solutions. I have air temp measurement in each room connected to a whole home control system. I have also buried a number of temp sensors in the slab / screeds. I can use that information to do what I want but don't intened to use it to control any heads at the manifold. Just plan to tweak the balancing and keep all open circuit.

Hi ,Andrew , your videos are extremely helpful, just want you advice, l want to further my career by studying on heating design, l was thinking to do a heat geek course, what would recommend much appreciated Gary

@andrewmillwardwatford9410

2 ай бұрын

Yes heat geek

Andrew, thank you for explaining this, it was very well done. Part of the difficulty I feel is ‘people’ desperately need the comfort factor of a rule of thumb. So when they see a credible video that suggests a buffer is not always necessary and can have a deleterious effect on efficiency this develops an almost Orwellian traction ‘two legs bad, four legs good’. ‘Most properties’ in the U.K. do not have mixed emitters (UFH &Rads) and this do not require the isolation offered by a buffer but because of other considerations (system volume/cycling and defrost) may require a volumiser. Which brings us onto the subject matter of this video, mixed emitters [UFH and Rads) require different flow temperatures - or do they? Can we not design the radiator circuit and their emitters to the design flow temp of the UFH? Or have I missed something?😉👍

@andrewmillwardwatford9410

2 ай бұрын

Yes you can design radiators and underfloor heating in theory to have the same mean water temperature. Buy designing underfloor heating to run at a higher temperature then it needs to you can make it work at the same temperature as your radiators. While this is great in theory the errors involved in calculation and application can leave you with temperature differences resulting from those errors. If you design both systems to run lower temperature as possible and fit a variable temperature mixer on the underfloor heating you're not only gain controlled but you gain some advantages from the application of a buffer. If secondary controls worked correctly then a buffer would almost always be an asset to a system. Just imagine if you control the flow rate on the secondary side when it was fitted on a single emitter system. You could gradually charge the buffer during a normal cycle to prepare it for a defrost cycle. During the defrost cycle you could turn off the pumps on the secondary side and just use the volume of heater available from the buffer to carry out the defrost. With this strategy there would be no dropping temperature within the system itself and only from the buffer. The same system could be employed to prevent cycling or at least to reduce cycling. As the heat pump reaches the point at which it would normally shut down it could then change low speeds and use the volume of the buffer to delay the cycle. Again by using pump control it could then use the volume of heat stored in the buffer to supply the system and prolong the off period of the heat pump. It's not difficult to imagine someone designing a simple control system that would give us these advantages from using a buffer. In my opinion the advantage of not having a buffer is simply one of space saving. Also until we have the correct controls to operate a buffer to our advantage there seems very little point in fitting one on a single emitter system if we have sufficient residual pump head from the heat pump. Also buffers could be very badly designed as they are by Daikin. The Daikin pre plumbed cylinder has a buffer which is short and fat, exactly the shape we don't want. With this buffer we get a raised return temperature to the heat pump due to the heat pump recycling its own flow water while at the same time the system has the same issue. This causes the heat pump to have to run at 5 degrees centigrade higher than it should at all times. If you look at the c o r n o t cycle you can see that at lower temperatures efficiency caused by this raised temperature can be exponentially bad.

@brotherjohnno

2 ай бұрын

Andrew, your extensive knowledge never fails to amaze me, you are really raising the bar. Much respect 👍

@andrewmillwardwatford9410

2 ай бұрын

@@brotherjohnno thank you

@jsimnable

2 ай бұрын

@@andrewmillwardwatford9410 I'd be interested in hearing more about controls for the secondary side. I just had a system like this installed (buffer with single zone, low temp mixed emitters). There is a valve that separates the two sides during defrost. The secondary pump seems to just drag down COP though. I can see the advantages of a single pump with volumizer instead of buffer - but I've also heard that two small pumps are more efficient than one large. Mine are single speed pumps though, and don't seem very efficient. So I just don't know...

@andrewmillwardwatford9410

2 ай бұрын

@@jsimnable the concept of controlling the secondary pump is not on any of the heat pumps available at the moment as far as I know. Someone indicated that stable eltron may have such a system on their heat pumps but I have not confirmed this. If you're Buffer and secondary pump is reducing your scop it must be incorrectly set up. You can try to reduce the flow on the secondary side to ensure that the heat pump flow is equal to or greater than the system flow. Obviously a match is the best possible objectives but higher flow on the secondary side is the least desirable situation.

Would you recommend me doing the heat pump courses in your opinion?

@andrewmillwardwatford9410

2 ай бұрын

What heat pump course are you referring to

pedantic of me I know, but at 8:35 you say you are transferred the 5.32 across and it becomes a minus. I see lots of people making mistakes (usually with multiplication/division but also addition/subtraction) with manipulating equations so I'm very keen on people doing this properly and subtracting 5.32 from each side of the equation rather than moving things across from side to side.

@andrewmillwardwatford9410

2 ай бұрын

You make a good point. My wife is a graduate of Economics and was helping me with the algebra. I was actually doing exactly as you said and applying in this case division to both sides. She has been educated in Estonia and she found this rather strange as she was taught simply to transfer it from one side to the other. Also in the video I'm using a simultaneous equation but using the Swedish method. This method is so simple that I don't think most people will recognise that I actually did it. Did you spot the simultaneous equation?

Mathematics you have to prove.How are you getting your flow rate have you got a flow gauge before or after your low loss header,how are you getting your temperature what are you using most thermometer have a +- of 2 degrees.my LLH the water coming in is not going straight to the radiators as I have a thermometer either side 40 coming in 30 going out the return is always hotter than the flow to the radiator why what maths works that out Hp has a pump and after the LLH there is a pump.

@andrewmillwardwatford9410

2 ай бұрын

I don't really understand what you are saying but I think you're claiming your heat pump or boiler return is hotter than the flow on the secondary side?

@Allegedly2right

2 ай бұрын

@@andrewmillwardwatford9410 where and how are you getting your flow rate and temperature.mine the readings are after the return LLH.The water mixes in the LLH so is not reading the radiators,I know cowboy-fitted it and ran away that’s life.Thanks for your reply

@andrewmillwardwatford9410

2 ай бұрын

@@Allegedly2right this video just explained theory and mathematics it wasn't the video on measuring. When I'm in the field I use contact type k thermocouples

@Allegedly2right

2 ай бұрын

@@andrewmillwardwatford9410 Andrew as I do either side of the low loss header 2 pipes on the left and 2 on the right flow and return T1&T2 the water just seems to come in and and circulate straight back out without going to the radiators all the readings are on the return after the LLH this is the point I am trying to point out and this is off Grants diagram for fitting.2 pumps how do you regulate them no one is saying how none of them Mathematical you have to prove 2x2=4 Heat Pumps = Smoke and Mirrors the lot of them.Just look at the Yanks they really know plumbing.Thanks for your interest haha Summer get that SCOP up now who came up with that con 6 month of the year off haha Snake Oil salesman for sure.