Hive heating & hot water to boilermate A class

[Bendo]

Hi all. Fitted my hive a few years back, but only to the heating side of things. After a lot of testing, it's clear that the boilermate is more efficient when it is only heated when needed. Though the summer I set the timer for a couple of hours each morning and this leaves plenty of water for the day with reasonable gas usage. Obviously in winter it needs to be charged to run the heating so now want to connect the hive hot water side.

From the wiring diagram (http://www.gledhill-spares.net/documents/BMAClassOV-Iss8.pdf), it looks like what is needed is to disconnect the existing front panel controls (clock and hot water / heating switches) and instead connect the hive where they were originally connected.

Following the wiring diagram, the current connections to Sl-W and SL-H lead to the rocker switches. I believe I need to disconnect these (and the associated live / neutral that goes to the clock) and connect them to the respective terminals on Hive
(CH on / HW on) and also connect SL-R to L2 in place of the existing connections to Hive.


Thanks in advance for any pointers.

 

[ianmcd]

Yes that is how you do it , but you would have been better getting a single channel hive and always leaving the store at temp for your HW, it will work what you are trying to do but not what that system is designed for, you might find your gas usage actually increases rather than decreases when you do this

 

[Bendo]

Thanks Ian. Over the past year I've done a lot of experiments, left to do it's own thing, it will burn through about 14KWh of gas. Run for a few hours in the morning it's more like 8. Have got gas usage down significantly this way.

My plan is to put the hive into gravity mode which will turn the water aspect on when the heating is run so I can schedule the morning heat and it will heat when necessary when heating is on.


I do have one final question which may be better asked elsewhere. The boilermate has an emergency switch feature - basically a 6KW electric heater. I assume mostly the make up of the pulsacoil electric version (although I don't believe that one does heating). I'm on Octopus Agile and so considering using the switch mode to power it when plunge pricing is on, basically getting paid to run the heating. However obviously it's described as for emergency use possibly because who would want to heat it on electric without such a tariff. Is it likely to cause problems using it this way though. I've tested it and it works nicely, but is it a good idea long term. I'm considering putting a smart switch in to enable it automatically by a home assistant automation when electric prices are negative.

 

[flameport]

but is it a good idea long term

Long term that Boilermate needs to be thrown into a skip.
It's an energy wasting pile of problems. Don't waste any money on it.

 

[ianmcd]

My plan is to put the hive into gravity mode which will turn the water aspect on when the heating is run so I can schedule the morning heat and it will heat when necessary when heating is on.

You will have to do that anyway or it wont work, but that is where the problem lays, the store must be up to temp for the CH to work, it is cheaper to keep the core up to temp than it is to , get it up to temp when it is cold, your heating will not come on until the core gets satisfied, really bad appliances , but it is what it is , if you can afford it , skip it and get a better system, if not, then stick with it but it will by design be expensive to run

 

[Bendo]

Long term that Boilermate needs to be thrown into a skip.
It's an energy wasting pile of problems. Don't waste any money on it.

Yes, I've seen that said so many times on here and elsewhere, but in reality in the 10 years I've lived here, it's given me precisely zero problems.

Heating the store in the morning uses about 8-10 KWh of gas and provides showers for 3 people and enough general hot water for the rest of the day. Sure, other options may use less gas but given the house was built in 2007, the rads are all undersized for condensing so they would all need replacing too, no replacement now is going to pay for itself and stuff like unvented is likely going to cost more factoring in its annual service.

Oh and yesterday I ran it on Electric for several hours with Octopus Agile plunge pricing, managed to chew through about 20KWh of electric so got paid to run the heating in effect.

 

[Bendo]

You will have to do that anyway or it wont work, but that is where the problem lays, the store must be up to temp for the CH to work, it is cheaper to keep the core up to temp than it is to , get it up to temp when it is cold, your heating will not come on until the core gets satisfied, really bad appliances , but it is what it is , if you can afford it , skip it and get a better system, if not, then stick with it but it will by design be expensive to run

Indeed, hence my desire to get it done now winter is coming. My experience based on lots of experimenting is that charging the store only when needed is much more efficient than leaving it to its own devices.

Combined with running it off the "switch backup" when plunge pricing is in effect, I don't think much come close in terms of running costs.

 

[flameport]

but given the house was built in 2007, the rads are all undersized for condensing so they would all need replacing too,

All gas boilers were mandated to be condensing from 2005, so if you have radiators that can't work with a condensing boiler, the original installation didn't comply with Building Regulations.

 

[Bendo]

Sounds like I'm mistaken then and the boiler probably is condensing, it just generally works so clearly not paid much attention to it. Still think the rads are generally undersized though.

Managed to get down to about 10,000 KWh of gas, only charging the store when needed should being that down a little bit more and that's with heating rooms to about 23 degrees (my wife isn't well and feels the cold).

If there was savings to be made I'd rip it out and have it replaced, but at this point, I don't think there would be any worthwhile payback.

 

[flameport]

Your boiler almost certainly a condensing one, but it will never have been used in that way, as heating a thermal store to the temperature of molten lava is exactly what condensing boilers should never have been used for.

Really a question of whether you want to continue with a system which is inefficient by design, or replace it for something which was designed properly and can actually be used as intended.

 

[Bendo]

Double checked, seems I was wrong about the year it was built despite being 2007 on the paperwork, looking at sold dates on land registry they were old sold Sept 2006 onwards.

Boiler is a Glowworm Micron 30Ff so not condensing, perhaps Persimmon had some dodgy paperwork going on.

I'll keep it until it dies though, it's efficient enough, heats the house well and doesn't cost a fortune to run along with no annual services for an unvented cylinder. Deff wouldn't even consider a combi..

 

[Bendo]

Just to wrap this up. Came to do it and as I was sat in front of it identifying the wires, noticed a lot of corrosion at the bottom. It's leaking a bit so will get someone out to advise on its replacement.

Sad times.